Seeking Advice on Building a Box-Fit Fucker

This is likely a long shot. I don’t know much about constructing things. Meaning, while I’m reasonably intelligent and handy, show me an engine and I’d be clueless on what to do with it. But I can definitely locate a solid DIY step-by-step tutorial online.

I want to build a fucker that fits inside a toolbox (for privacy). Something not too hard to put together. A stroke length of 4-6 inches would be ideal. There’s all this talk about DC motors and such, which confuses me. I understand the concept of turning rotation into linear motion, so I’m confident I can sort that out. The tricky bits are the wiring and power supply, plus adjusting speeds. The fukbox seems like what I want…but I don’t feel like paying $20 for the schematics. Especially if they aren’t all that useful to someone with my knowledge level. If anyone has built a fuck machine before, please let me know. I’d appreciate some ideas, insights, and guidance. My target budget is around 200$.