Include the essentials
Share the native CAD file when appropriate, plus a neutral export such as STL, STEP, or 3MF. State the quantity, units, target material, finish, and deadline in the request itself.
If the part is one component in an assembly, include a screenshot or simple description of what it connects to and which dimensions matter most.
Call out constraints
Mark holes, threads, mating faces, snap fits, moving clearances, and other critical features. If you have a tolerance requirement, write it down instead of expecting the supplier to infer it from the model.
For visual parts, describe the expected finish and acceptable layer lines. For functional parts, describe the loads and environment that matter.
Make the quote easy to compare
Ask each partner to return price, lead time, process, material, finishing assumptions, and delivery terms. Consistent information makes the decision easier and protects both sides from surprises.