Cost: 5-10 usd
Step 1: Gathering the junk
Those are the old bellows (preferibly 35mm, brand doesnt matter as long as they are light tight), a body cap for your dSLR (skip this part if this is for a point and shoot) and some way to mount the lens.
Also needed is some 5 min epoxy, a file, a knife/drill, electric tape.
In this case i bought a titan body cap (to fit a nikon ai mount) and i used the cheepo lens cover that came with the kit lens. My bellows were given to me as a set of junk cameras and are Miranda Focabell s. Whatever that means. No camera came with is, so its junk. If you can not find bellows in your basement or local pawn shops, check ebay. Remember, any crappy bellows will work.