The 2N2/256-BSCP [was: Homebrew Drum Computer]

Rather than a magnetic drum, I think a much more achievable contraption is a drum that uses capacitance for storage. The density would be much lower, but it would be more tractable, I think. Inside a hollow cylinder mount rows of capacitors. One side of all capacitors would be connected in common to ground, which conveniently would also be the axle that would be spinning the drum. The other side of each cap would punch through the cylinder wall with a brass stud. A row of brushes would make contact with a row of caps at a given time. Just like a DRAM, you'd have to read, sense, and refresh the caps on each read, and every so often in case a given word wasn't read for a while. To make things simple, read, sense, and refresh every rotation to get rid of any special cases.