Hi, I am designing lots of parts to be 3D printed. In SW, things work out exactly but once the objects are 3D printed, they may not fit. For example, I have a 3cmx3cmx3cm cube. I want to make a case that just fits the lower half of the cube. Should I set the dimensions of the case to be exactly 3cmx3cmx1.5cm and hope that when it is printed, there will be some variations and due to the flexibility of the materials, it could work or make it like 3.01cmx3.01cmx1.5cm or 3.1cmx3.1cmx1.5cm? Is it more like trial and error. i.e. print it out and see if it fits. If not, make it a bit larger? Or is there a general guideline such as making everything y mm longer?

Making everything in exact dimensions makes it easy to design complex assemblies in SW as all I need to care is they "just fit" and all get lined up in the SW models. Designing with some tolerance in mind may be more difficulty.