My poorly articulated point is not everybody can do that.You build your designs in CAD, save as .stl, slice and print. It's really easy. There are plenty of free CAD suites available.
Don't forget on GTT most members are of superior mechanical intellect...
I usually don't need a full blown model to give my cnc guys tool path. I can assign tools to two dimension geometry that can be drawn in moments.
The couple times I had to create solids to suggest to customers' engineers when trying to illustrate design changes to reduce production costs. Gave me a massive headache...
I have no training and have only done it a couple times though, may be too old to learn new tricks anyway.