>>2053968
How folding are we talking?
If a 26-er that folds in half is good, then go on Aliexpress, find one of those frames for ~100 bucks, and source a local donor bike for your budget to transfer everything over. It'll be a full-on bike, no different from what you built it out of, just able to fit in your closet, in your car's trunk and allowed in places where only folding bikes are allowed. It's much bigger than a Brompton obviously, but compared to a regular bike, it adds a lot of practicality.
Make sure it's one that pivots around the seat tube, Paratrooper-style, not one that folds at the top tube, these break in half.