Here's another project with freely available Eagle project files.

There was a strange little thing that appeared in Danish magazine Ny Elektronik (New Electronics) in 1989. A very simple preamplifier that used two L63 tubes in Class A with no feedback and it operated pretty much badly out of spec. (...

Here's a little side project, and it comes with Eagle Project files so you can order, etch and modify it anyway you like. All project files are available on this Hackaday.io project page: https://hackaday.io/project/18624-muffsy-constant-current-led-tester