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  <xsd:element id="prlb_DeferredTaxLiabilityCaresAct" name="DeferredTaxLiabilityCaresAct" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="prlb_DepreciationAndAmortizationByGeographicRegionTableTextBlock" name="DepreciationAndAmortizationByGeographicRegionTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_DocumentAndEntityInformation" name="DocumentAndEntityInformation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element id="prlb_EffectiveIncomeTaxRateContinuingOperationsIncreaseDecreaseDuringThePeriod" name="EffectiveIncomeTaxRateContinuingOperationsIncreaseDecreaseDuringThePeriod" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_EffectiveIncomeTaxRateReconciliationProvisionToReturnDifferencePercent" name="EffectiveIncomeTaxRateReconciliationProvisionToReturnDifferencePercent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_EffectiveIncomeTaxRateReconciliationQualifiedSubsidiaryElection" name="EffectiveIncomeTaxRateReconciliationQualifiedSubsidiaryElection" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTaxLiability" name="EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTaxLiability" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_EffectiveIncomeTaxRateReconciliationTransitionTaxPercent" name="EffectiveIncomeTaxRateReconciliationTransitionTaxPercent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_EmployeeStockPurchasePlanOfferingPeriod" name="EmployeeStockPurchasePlanOfferingPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_EmployeeStockPurchasePlanWeightedAveragePurchasePriceOfSharesPurchased" name="EmployeeStockPurchasePlanWeightedAveragePurchasePriceOfSharesPurchased" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_EuropeSegmentMember" name="EuropeSegmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_ExercisePriceRangeFourMember" name="ExercisePriceRangeFourMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
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  <xsd:element id="prlb_ExpendituresForAdditionsToLonglivedAssetsByGeographicRegionTableTextBlock" name="ExpendituresForAdditionsToLonglivedAssetsByGeographicRegionTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_IncomeFromOperationsByGeographicAreaTableTextBlock" name="IncomeFromOperationsByGeographicAreaTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_IncreaseDecreaseInIncomeTaxesPayableCaresAct" name="IncreaseDecreaseInIncomeTaxesPayableCaresAct" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
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  <xsd:element id="prlb_LesseeLeaseLiabilityMaturityTableTextBlock" name="LesseeLeaseLiabilityMaturityTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_LesseeOperatingLeasesAndFinancingLeasesTextBlock" name="LesseeOperatingLeasesAndFinancingLeasesTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_LongtermIncentivePlan2012Member" name="LongtermIncentivePlan2012Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_MinimumNumberOfEmployeeWorkingHoursRequiredToBeEligibleToParticipateInFourZeroOneKPlan" name="MinimumNumberOfEmployeeWorkingHoursRequiredToBeEligibleToParticipateInFourZeroOneKPlan" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_MinimumServicePeriodOfEmployeesToAvailBenefitUnderDefinedContributionBenefitPlan" name="MinimumServicePeriodOfEmployeesToAvailBenefitUnderDefinedContributionBenefitPlan" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_NoteToFinancialStatementDetailsTextual" name="NoteToFinancialStatementDetailsTextual" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element id="prlb_OperatingLossCarryforwardsPercentageOfTaxableIncome" name="OperatingLossCarryforwardsPercentageOfTaxableIncome" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_OtherProductsMember" name="OtherProductsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_PercentageOfTargetNumberCapableOfBeingEarnedAndVestingLowerLimit" name="PercentageOfTargetNumberCapableOfBeingEarnedAndVestingLowerLimit" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="prlb_PercentageOfTargetNumberCapableOfBeingEarnedAndVestingUpperLimit" name="PercentageOfTargetNumberCapableOfBeingEarnedAndVestingUpperLimit" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="prlb_ScheduleOfLeaseExpenseTableTextBlock" name="ScheduleOfLeaseExpenseTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_ScheduleOfLeaseTermsAndDiscountRatesTableTextBlock" name="ScheduleOfLeaseTermsAndDiscountRatesTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_ScheduleOfSharebasedPaymentAwardAwardsOtherThanStockOptionsValuationAssumptionsTableTextBlock" name="ScheduleOfSharebasedPaymentAwardAwardsOtherThanStockOptionsValuationAssumptionsTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="prlb_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceChange" name="SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceChange" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="prlb_statement-statement-note-13-leases-maturities-of-operating-lease-liabilities-details" name="statement-statement-note-13-leases-maturities-of-operating-lease-liabilities-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="prlb_statement-statement-note-13-leases-weighted-average-remaining-terms-and-discount-rates-details" name="statement-statement-note-13-leases-weighted-average-remaining-terms-and-discount-rates-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="prlb_statement-statement-note-15-income-taxes-components-of-income-loss-before-income-taxes-details" name="statement-statement-note-15-income-taxes-components-of-income-loss-before-income-taxes-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-15-income-taxes-reconciliation-of-beginning-and-ending-amount-of-unrecognized-tax-benefits-details" name="statement-statement-note-15-income-taxes-reconciliation-of-beginning-and-ending-amount-of-unrecognized-tax-benefits-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-15-income-taxes-reconciliation-of-federal-statutory-income-tax-rate-to-effective-tax-rate-details" name="statement-statement-note-15-income-taxes-reconciliation-of-federal-statutory-income-tax-rate-to-effective-tax-rate-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-15-income-taxes-significant-components-of-deferred-tax-assets-and-liabilities-details" name="statement-statement-note-15-income-taxes-significant-components-of-deferred-tax-assets-and-liabilities-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-15-income-taxes-significant-components-of-provision-for-income-taxes-details" name="statement-statement-note-15-income-taxes-significant-components-of-provision-for-income-taxes-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-15-income-taxes-tables" name="statement-statement-note-15-income-taxes-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-17-segment-reporting-depreciation-and-amortization-details" name="statement-statement-note-17-segment-reporting-depreciation-and-amortization-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-17-segment-reporting-expenditures-for-additions-to-longlived-assets-details" name="statement-statement-note-17-segment-reporting-expenditures-for-additions-to-longlived-assets-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-17-segment-reporting-income-from-operations-details" name="statement-statement-note-17-segment-reporting-income-from-operations-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-17-segment-reporting-longlived-assets-by-geographic-region-details" name="statement-statement-note-17-segment-reporting-longlived-assets-by-geographic-region-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-17-segment-reporting-revenue-from-operations-by-reportable-segment-details" name="statement-statement-note-17-segment-reporting-revenue-from-operations-by-reportable-segment-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-17-segment-reporting-tables" name="statement-statement-note-17-segment-reporting-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-3-revenue-disaggregation-of-revenue-details" name="statement-statement-note-3-revenue-disaggregation-of-revenue-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-3-revenue-tables" name="statement-statement-note-3-revenue-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-4-net-income-per-common-share-computation-of-basic-and-diluted-net-income-per-share-details" name="statement-statement-note-4-net-income-per-common-share-computation-of-basic-and-diluted-net-income-per-share-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-4-net-income-per-common-share-tables" name="statement-statement-note-4-net-income-per-common-share-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-5-goodwill-and-other-intangible-assets-changes-in-carrying-amount-of-goodwill-details" name="statement-statement-note-5-goodwill-and-other-intangible-assets-changes-in-carrying-amount-of-goodwill-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-5-goodwill-and-other-intangible-assets-estimated-aggregated-amortization-expense-details" name="statement-statement-note-5-goodwill-and-other-intangible-assets-estimated-aggregated-amortization-expense-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-5-goodwill-and-other-intangible-assets-intangible-assets-other-than-goodwill-details" name="statement-statement-note-5-goodwill-and-other-intangible-assets-intangible-assets-other-than-goodwill-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-5-goodwill-and-other-intangible-assets-tables" name="statement-statement-note-5-goodwill-and-other-intangible-assets-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-6-fair-value-measurements-fair-value-of-financial-assets-measured-on-a-recurring-basis-details" name="statement-statement-note-6-fair-value-measurements-fair-value-of-financial-assets-measured-on-a-recurring-basis-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-6-fair-value-measurements-tables" name="statement-statement-note-6-fair-value-measurements-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-7-marketable-securities-balance-of-heldtomaturity-debt-securities-by-contractual-maturity-details" name="statement-statement-note-7-marketable-securities-balance-of-heldtomaturity-debt-securities-by-contractual-maturity-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-7-marketable-securities-shortterm-and-longterm-marketable-securities-details" name="statement-statement-note-7-marketable-securities-shortterm-and-longterm-marketable-securities-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-7-marketable-securities-tables" name="statement-statement-note-7-marketable-securities-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-8-property-and-equipment-components-of-property-and-equipment-details" name="statement-statement-note-8-property-and-equipment-components-of-property-and-equipment-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-8-property-and-equipment-tables" name="statement-statement-note-8-property-and-equipment-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-9-inventory-inventory-details" name="statement-statement-note-9-inventory-inventory-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-note-9-inventory-tables" name="statement-statement-note-9-inventory-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="prlb_statement-statement-significant-accounting-policies-policies" name="statement-statement-significant-accounting-policies-policies" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
</xsd:schema>
