JF Ptak Science Books Post 2074 History of Holes series
These are some of the earliest holes in one of the very first personal computers--they were made for ease of wiring and other applications in the Geniac, a 1955 DYI kit from the indomitable Ed Berkeley, a machine well in advance but much of course the inferior of the Mark 8 (1974) and the Altair 8800 (1975), the later of the two seen as being about the very first modern "personal computer". There weren't too many empty holes in those two machines.
What had no relays, or transistors, or tubes, and was manually self-sequencing and human bit state switching, the name ending in "-iac", and made in 1955? The "Geniac", made and manufactured by the smart and enterprising Edmund Berkeley and Oliver Garfield--the "Genius Almostt Automatic Computer". It was I think the first in a line of early non-computer-computer-that-really-was-a-computer-according-to-Alan-Turing computers that a person could own and own at home, and it was followed pretty close on heals by the Tinyac, the Weenyac, and the Brainiac.
[Source: Dr. Gangrene, here.]
The Geniac was/is a pretty neat tool--I hesitate to call it a "toy" as others have, mainly because it takes itself pretty seriously and still have fun, and includes diagrams and drawings for interesting sets of problems and tasks, from playing tic-tac-toe, to "testing" I.Q., to determining the male/female-ness of the respondent, to playing a very very mildly interactive game of uranium prospecting and alien hunting. It was a fine construction, and introduced the user to Boolean equations and the concepts of a working computer, all with hands-on education and a dry cell power course. And that's pretty good.
[Source: Blinkenlights, here.]
Geniac Study Guide, via Computercollector.com (for the rest of the document):
Wiring diagran for the Uranium Shipment and Space Pirate game, again, via the computercollector.com
See also the GENIAC entry at the Old Computer Museum, here.