Picture of mini circular bench saw from scrap. This could be usefull. But defenatly done a whole hell of a lot better.
Isotron 160 meter vertical
Radio-Kits - MKARS80 LSB QRP Transceiver
homemade revers crossbow plans and elements measurements - YouTube
Slingshots and blow guns can be interesting to try out at the range or in your backyard.
Slingshot... a quality one makes for a great addition to any survival kit. Easy to learn to use, ammo is plentiful, can be effective in hunting small game and for recreation.
Building a High Quality Slingshot with Rotating Bearings
Homebrew Collinear Antenna - from just a piece of solid copper wire!
A good starter 2 meter 1/4 wave ground plane antenna for < $10. I friend made…
Tutorial: Winding toroids - turn count - make sure the windings are spaced as evenly as possible on the core