Four years ago I was messing around with a stepper motor I had and was wondering if I could build a CNC machine from it. Started doing some research found this forum and realized not only was it possible, but fairly common and looked pretty easy. I didn't have a real goal in mind, just was playing around, so I didn't want to spend any real money on it. I ended up slapping together a handful of cheap stepper motors with some belts, and a frame made out of 2x4s. I had some old drawer slides laying around and I used those with an Arduino running GRBL to come up with the first version of my CNC.
All told I ended up using mostly spare parts laying around and spent less than $100 to get something that was kinda sorta functional! I was surprised at how well it work for how little I had in it. The biggest issue was really the dust getting in the drawer slides. Besides for that it was reasonably accurate and plenty repeatable enough for wood working. I made a bunch of little carvings and other random projects with it. I think it was a great introduction, and I learned a ton doing it. It was a great introduction to get some hands on experience without spending any real money.
I used the for a year or so making minor improvements to it here and there before I decided that it was worth spending some money on and improving it. This went on for the next four years slowly improving and redesigning this and that until finally today I'm at a point where I can make real aluminum parts in a reasonable time frame holding ~0.005" tolerances.
This is a manifold I finished up the other day:
I thought I'd like to share my journey and show a bunch of the iterations. Might help someone else avoid some of the pitfalls I made, or skip some of the intermediate steps. I'm also planning a big upgrade in the future, which I'm just starting designing now. Here's a teaser: