Material guidance
Choose for the job. Specify the fit.
Begin with the requirement, not just the colour or a familiar material name. This guide explains general considerations; the options available for your order are confirmed separately.
Communicate critical dimensions with an STL or STEP file.
A model describes a shape. A useful brief also says which dimensions matter and how the part should meet another object. Add a short marked-up view so the important relationships can be understood without guessing from the filename.
1 / State the units and one overall size.
Write the intended units and length × width × height in the brief. STL describes a triangulated surface without a stored unit definition, so an importer's unit choice can change the interpreted size. Check an imported preview against the size you intended. A reference dimension helps expose a scale mismatch; it does not establish print accuracy. Autodesk's STL guidance
If you have STEP geometry, share its intended units, revision and the same dimensional notes. A file extension does not communicate whether a fit should slide or hold. Use the formats offered by the quote form; a STEP file or a design requiring changes may need a separate CAD enquiry. Do not convert or rescale geometry merely to conceal an unsupported format.
2 / Show where the measurement starts.
Mark the two faces or edges used for each critical dimension. “The slot is 20 mm from the edge” leaves a question: which edge, and which side of the slot? A marked plan and a second view can make that relationship clear. If a dimension is an estimate or has not been measured, label it that way.
The original sketch above uses a fictional 120 × 80 mm outer plan to illustrate communication. Reference edges A and B are descriptive labels, not a formal GD&T scheme. The arrows identify the surfaces to specify; the drawing is not to scale and is not a production drawing or a dimensioned CAD model.
3 / Describe the fit you want.
For a sliding cover, identify the groove and the lid edge that moves through it. Say whether easy movement, low play or retention matters most. A nominal clearance is the designed separation; a tolerance is the permitted dimensional variation. They are different parts of the specification. The acceptable relationship needs deciding for the intended function. Formlabs on fits and tolerances
AI-generated illustration of a fictional sliding interface. Notice the groove and the entering lid edge; their exact cross-section and fit are schematic, with no measured clearance or manufacturing result.
- Groove: state its intended width and the faces used to define it.
- Lid edge: specify the matching feature and required movement.
- Insertion direction: travel along the long rail; the arrow is an editable concept annotation.
For a simple opposed pair, total nominal lateral clearance = slot width − mating-part width. If the part is centred and the two sides are symmetric, the nominal gap per side would be half that difference. This arithmetic is an illustration of the definition, not a recommended printable value. Actual geometry, corner radii, surface condition and dimensional variation also matter. Show whether your number means total clearance or clearance on one side; do not write only “add a gap”.
4 / Identify priority surfaces and use conditions.
Mark the rail face, pocket seat or visible surface that matters. Say if support marks there would affect the purpose, and describe the environment and movement. Process, orientation and material affect the dimensional discussion; there is no single gap that works for all printed parts. Prusa's modelling guidance
Choose from the actual options offered for the order; a polymer family or resin label is not a finished-part performance guarantee. Resin formulations can require different post-curing conditions, so use the applicable material instructions. Formlabs' curing guidance
5 / Separate a design input from a checked result.
Use wording such as “intended slot width”, “measured object outline” or “clearance still to be agreed”. A rendered tray, drawing or preview cannot establish that the real object will seat, lift out or stack as intended. For a critical fit, agree what would count as acceptable and how the physical relationship will be checked.
A short dimension checklist
- Intended units and overall length, width and height.
- Correct file revision and quantity, with mating parts identified.
- Critical dimensions with their reference edges/surfaces shown.
- Required movement, location or retention; distinguish total and per-side clearance.
- Measured values, assumed values and unresolved dimensions clearly separated.
- Important faces, working conditions and any required fit check.
Compare the sliding lid and nested tray studies. With ready geometry, start an online quote; for geometry creation or changes, ask about CAD help.
Five useful things to tell us
Explain what the part does, where it fits, how it is loaded, the conditions around it and which surfaces matter. A material that suits a shape study may not suit a component left under load in a warm environment.
FDM and resin are confirmed services. The families below are educational examples, not a stocked-material menu. Exact grades, colours and process options depend on the enquiry.
Filament families
- PLA is often considered for visual models and early prototypes where demanding heat or mechanical performance is not the aim.
- PETG is a common practical filament family, but its name does not make it suitable for every bracket or housing.
- ASA is often considered for outdoor exposure; the actual grade and use conditions still need assessment.
- Flexible filament families such as TPU introduce questions about hardness and deformation as well as shape.
- Nylon, PC and filled composites have their own formulation and processing considerations. They are not automatically stronger in every situation or confirmed available here.
Resin is a family of choices too
Resin formulations can serve different purposes. The exact material, geometry and appropriate processing matter more than the generic process name. Cleaning and grade-specific curing requirements must be followed for the intended result.
An attractive detailed print is not evidence of a certified material or suitability for medical, food-contact or other specialised use.
Turn guidance into a project specification
Once an actual material is proposed, compare its relevant technical information against the part and its working conditions. The same polymer family can include different grades, and a supplier test specimen is not your finished geometry.
Tell us which requirements are essential and where you have flexibility. That makes the process and material discussion more useful.
Bring your next part
into focus.
