My first EVER 3D design was this little guy. I used Alibre, which is a program and company I loathe. I designed that case to fit a tiny circuit board I designed. It is a delayed shut down motor controller to replace a funky bimetal “time delay relay” that industry stopped making but was still in demand. The design had to fit every known usage case. Case came first, then the circuit board which is under the epoxy. The epoxy is not supposed to be covering electrolytic cap and 30amp automotive relay. Tiny little 8 pin Microchip MCU and about 20 lines of code. Initially for RV furnaces but it is used in other applications. Wish I had today’s Shapr for that one. The case is injection molded.
The mold maker called me and asked for “Draft Angle”. I had to learn what that was and resubmit the project. Luckily Alibre handled that well. They sent a 3D printed version, but the 3 little round flat topped pegs to set the circuit board slightly off the bottom of the case were translated as holes instead. Luckily they sent that “mock up”. 3D printing at the time was not really at consumer level. Save some grief. Molds are expensive and often amortized in part cost over time until it is paid off. Back then a cheap mold was > $10K.
Now I would definitely have asked management to buy a couple 3D printers and just print the case.