Any ideas?
I’ve seen a couple handmade/manual.
http://chaokhun.kmitl.ac.th/~kswichit/easy1pcb/Jumpline.jpg
How would I do that?
This sure is easy, but you won’t be able to do a CORE module layout with this ;D
You just “draw” your traces directly onto the copper-plated PCB with a resistant marker-pen. Then you throw the PCB into your etching solution (like FeCl3), wait, take it out, clean it, remove the ink with alcohol, and ta-daa 
I did my modules with the “Iron-on” method, as mentioned in the wiki.
In the old days we used the nail polish to draw the lines. They were not smooth, but the laquer was holding strong. 