We built a homemade DIY Spot Welder, but ours is very different from other videos you find online. Why? Well because it doesn't require you to have a big machine shop, or even just a drill, a welder, or metal bending equipment, ALL YOU NEED IS A 3D PRINTER (and a soldering iron). The designs include just 4 simple 3D printed parts, and once you get those, this build should take no more than one day. 

McMaster-Carr Parts With Part Numbers:
1. Alloy Steel Cone-Point Set Screws - 92695A310
2. Aluminum Set Screw Lug - 6920K24
3. Equipment-Cooling Fan - 1976K91
4. IEC Connector With Power Switch - 5428N125
5. Steel Hex Nut M4 x 0.7 mm Thread - 90592A090
6. Welding Wire - 7940A93