ABS filament diameter can change over time. Every once in a while you need to trust if two parts are going to mate propertly. So if you've just changed filament rolls make sure you know what your filament diameter in should be in RepG by printing this small object.I actually made this to see if I could use it for my chess set, but it has been useful since then too.Print this object then try mating the two parts together. (PROTIP, name the S3G file with the filament diameter for future reference.)If when you put the two parts together they're too tight no matter how you push they don't go then raise your filament by 0.04mm. If they go together with a lot of effort but don't come apart raise your filament diameter by 0.02mm. If they go together but then fall apart the lower your filament diameter by 0.02mm. Then repeat the tests until they go together, hold, and come apart with ease. Then use that filament diameter for the rest of your tests.