
SmartAz writes- This no-frames, no frills website is dedicated to those brave experimenters spending time in building their own backpacking stoves or modifying commercial made ones. New designs are added from time to time. Currently the site has 28 designs with costs ranging from zero to ten bucks, depending on whether you buy materials or find them. Link.
I’ve made my own Pepsi can stove to use on backpacking trips and it works great! It as inexpensive as you can get and boils water in just a few minutes.
Here’s a great link to more DIY camping gear.
I made the the Go-Torch stove.