"Foxhole radio" are search engine keywords. Complete kits are
available, the one I have was sold by Cornell radio, eham has reviews.

Rectifier hints:

Vintage Gillette Blue Blades got their color from factory fire
hardening which also made them semiconductors.

Ebay always has cheap packs of wwii era single edge blades.

The best pencel lead size is widely rumoured to be #2, for some odd
reason.