I started by looking at letterpress designs at briarpress.org, and, it seemed to me anyway, the basic functioning of Gutenberg's model could be relatively easily reproduced on a small scale and a small budget.
Of course, it ended up taking a while, but the invitations got out on time.
Step 1: Construction
What will you need? These things:
1. Two 4'x8' sheets good quality 3/4" plywood (find stuff with relatively few gaps, there's going to be a lot of pressure involved in this).
2. Six 18" lengths of 1/2" diameter all-thread ( I think I found 36" lengths and cut them in half with a hacksaw; if you do this, be careful not to screw up the thread too much when cutting).
3. Nuts & washers to fit the all-thread. You'll need a total of 24 of each. It was cheaper, if I recall correctly, to just buy a box of each.
4. A veneer press screw. I used this one.
5. Some cork board. I found 12" square pieces in a six-pack at Ace.
6. Wood glue & a couple of wood screws.
1. A table saw to deal with the plywood
2. A drill press (with relatively long 1/2", 11/16", & 1" bits)
3. Various pliers, wrenches, maybe a hammer, a glue brush, etc.
1. The ability to divide & multiply fractions (I'm sadly lacking here).
2. The ability to measure relatively accurately (this, I can do).
1. This is scalable. Make it bigger, make it smaller. This version has a maximum press area of 12"x12" in theory, and probably a little less effectively. There are bigger, heavier duty press screws out there that would probably be appropriate if you went up to something like 16"x16".
2. A lot of this, especially as we move toward the actual printing, was engineered on the fly. It works for me, but I'm sure there are better ways to do some of this. Fix it up.