Nice project! Is that for patrolling the sky, or for target imaging? 85mm is too much for the first task (I have experience building bolide patrolling camera) The 3D printing prototyping is a game changer, as you can define and use special settings to save time and filament printing your draft parts. Also the software allows you to slice larger parts and merge components later, so you can test-print fragments of your prototypes i.e. for best fit tuning (by the way, there are certain specifics for tight fittings design of 3D printed parts). At the moment I'm waiting for the Black matte finish ABS filament in the mail to start fiddling with optical attachments to my telescope. So far I've printed several end caps and boxes to my eyepieces, focusers, binoculars, the universal binoculars tripod mount with green laser pointer holder (the later went through 4 prototypes), many other small things (e.g. some weird Lego parts for my DS ). Another nice project still in the development - the custom high rise stock shoulder pad for my Saiga-12 kushnapup (bullpup) conversion with AK tools capsule holder.

To answer your question - see my extended post on that above
In short: try to obtain the SolidWorks - truly ultimate solution.