Hi Mike, your question seems to imply that you may be using the incorrect software to develop your design. It sounds as if you are using surface modeling software (like Blender) instead of a CAD package. You should try software like Fusion 360 and Solidworks that can detect poor geometry with tools like validate model and solid check. Solid check is especially powerful as it can detect invalid/open surfaces as well as edge/surface gaps.

Noah has made some good suggestions, but it’s important to note that it can be difficult to become proficient with using this software. If you are already using surfacing software to design your parts you might find it easier to import the geometry into these CAD packages and just make use of the geometry check and drawing features.