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- You almost always have less room than you think.
- CAD models do not generally include free connectors or wires: keep them in your head throughout design - wires (especially connectors) don't have zero thickness and can't bend at extreme angles
- A totally packed design is impossible to physically access - you will have a bunch of empty space for the simple reason that you need to reach things
- Have a small ruler on hand while designing.
- Being able to zoom in arbitrarily makes designing geometry too small to be usable (comfortably or at all) too easy, and it's often helpful to ground yourself to something.
- CAD screws at some point. Their heads are non-negligible.
Actively consider wiring paths, connector placement, and physical access during the design phase. Wires do not have zero thickness and cannot necessarily bend at extreme angles- If you have boards on two sides of an avionics sled, modeling screws lets you make sure they don't interfere with boards or screws on the other side.
- High-power transmitters have non-negligible heat output. It is possible to melt printed mounts.
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