Preparing Your 3D Model for a Print Service: The Handoff Checklist

A print service needs more than a model that opens. It needs to know what size to make it, what the part does, and which details cannot change. This checklist is for handing a file to another person, not repairing its triangles. For that, use the export and mesh-repair checklist.

1. Identify the File and Its Dimensions

Give each revision a distinct filename, such as sensor-bracket-r03.stl. Include quantity and overall dimensions in millimeters. STL does not store a unit declaration, so a separate dimension is an important cross-check even if your CAD workspace uses millimeters.

Keep your editable CAD source. Send the format the provider accepts, and ask before substituting a STEP file, mesh, or slicer project. A 3MF project may carry another printer's settings; it is not permission to run those settings on a different machine.

For an assembly, say whether the quantity means individual pieces or complete sets. Two lids and two bases are two sets, not four sets.

2. Describe the Application Before Choosing the Material

"Black plastic" specifies appearance, not performance. Tell the provider whether the part will be indoors, outdoors, near heat, under a sustained load, or exposed to a particular cleaner. Include the expected temperature, load direction, and what happens if it breaks when those are relevant.

If you know the exact filament grade, name it. Otherwise, explain the application and request a recommendation. Use the material selection guide to frame that conversation. No material name alone establishes food-contact suitability, flame resistance, or safe load capacity.

3. Mark the Dimensions That Control Fit

Overall size is not enough for a replacement part. Mark hole diameters, hole spacing, mating surfaces, and the face from which each dimension is measured. Say which dimensions are essential and which are cosmetic.

Printed keycaps illustrating small mating features

A keycap, for example, can look correct while its stem fails to fit the intended switch. Request a small test piece or one sample before a full set when fit has not been established. Do not ask the provider to scale an entire part to fix one hole: that changes every other dimension too.

If geometry needs changing, the tolerance and orientation guide explains the decisions to approve.

4. Agree on Finish, Timing, and Scope

Name the visible face and any surface that must stay free of support marks. Ask whether the quote includes support removal, sanding, inserts, assembly, and packaging. A print described as "finished" might mean only that temporary supports have been removed.

Give a required arrival date, not just "ASAP." Printing time is only part of the schedule: queueing, drying, setup, cooling, inspection, and shipping can add time. Confirm whether the provider is quoting a production estimate or a delivery commitment.

Agree on who approves changes and what triggers a new quote. A new revision, higher quantity, different material, or tighter fit requirement can change the work substantially.

5. Send One Unambiguous Handoff

Here is a fictional brief you can adapt:

File: sensor-bracket-r03.stl, designed in millimeters. Quantity: two identical parts. Overall size: 80 x 40 x 25 mm. Indoor prototype, no safety-critical load. Black preferred; please recommend a material. The two mounting holes and their 60 mm center spacing control fit; see the dimensioned drawing. Front face is visible. Support removal included; no paint. Please quote a fit sample first and confirm the delivery date before production. Do not modify the geometry without approval.

Replace the example's assumptions with the real requirements. A short, specific brief is more useful than a long message that leaves the units, revision, or intended use unclear.