Do any commercially available generic circuits use only discrete components?
You could buy used Digital Equipment (DEC) "Flip-Chip" boards, that were used in the PDP-8 and other computers 50 years ago.  They are available on eBay typically for $10 apiece.  (Search for "PDP-8 flip".)

There are NAND/NOR gates, inverters, flip-flops, one-shots, decoders -- all built using transistors and diodes.  (I believe some newer ones started to use IC's, so you would want to stay away from those.)

These cards were usually plugged into a backplane, and the pins on the back coming from the connectors were connected using wire-wrap.  (The linked article even shows the backplane of a PDP-8I.)

Here's a dual flip-flop:



Schematics should be readily available after a little searching.

You could also look into buying a used PDP-8 or other DEC computer in non-working order and get a whole lot of these.  Then you would also get the backplane and connectors.

Although wire-wrap isn't used that much anymore, the tools (including wire-wrap guns, much nicer than the little manual wrap tools) are available from Digi-Key and other sources, as well as 30-guage wire-wrap wire.