Prototyping perfboard cut to Eurorack panel widths, so a circuit you are testing can live in the rack instead of on the bench next to it.
Twenty boards to a pack, five each at 6HP, 8HP, 12HP and 16HP. Two rows of pads, trace-connected to the adjacent through-holes, which covers most of what a utility module or a one-off CV tool needs.
I still cannot quite believe these did not already exist. Eurorack is a hobby about building small circuit boards in a handful of standard widths, so blank board cut to those same widths is not much of a leap. Somebody must have thought of it already, but I guess never did anything about it. I could not find it anywhere, so I made it.
They are for sale on Etsy for $35 a pack.