Back when I was learning KiCAD and before I learned to make jumpers only at 90 degree angles. No idea what I was thinking with C-B-A-D but this was in the hazy years of trying pain killers of every sort after the broken neck and back… But I managed to figure out circuit design, op amps, offset currents, shunts, PCB layout, soldering, single and double sided boards, and both laser toner transfer (bottom) and photoresist (top) based circuit etching, plus using toner transfer like a screen print.