I threw together a hot wire cutter, using 44lb stainless leader wire from walmart, and some wood.
The power source is a 2 cell lipo, anything that will handle 2 amps will be fine, just be sure you don't
run down the battery to much (I use a 1300 mah 2S battery).
When I have printed plans, I use a spray glue to glue the plans to poster board (a good amount of glue), then cut out the poster board. To use them just lightly glue the poster board to the foam (just a little so it is tacky), then use the hot wire to cut out the part. It will cut through the foam, but not the poster board. Then when done, pop off the poster board from the foam.
The only note is to make sure you don't push on the wire to much with the template, this will push the wire over and give you a cut that is not 90 degrees.
1X8 24", 20", 20"
1X4 8.25", 8.25", 8.25", 8.25", 7", 7"
Hardware:Aluminum L braket (I used a piece of L channel I had)
1/4-20 threaded loop or hook (I started with a loop, but cut it down to a hook)
1/4-20 threaded rod (only a few small pieces used)
1/4-20 threaded nuts (13)
deck screws (any wood screws with a tapered head), mostly around 1.5 inches long (a couple need to be shorter, to not go through the 1" wood, which is really .75" thick)
small piece of alumninum C channel (mine was about 3/4" wide and 1/2" deep)
2 aluminum plates around 1.25" X 3" and 1/16" thick
Misc:44 lb stainless leader wire (I got mine at Walmart)
some wire to take current from the battery to the leader wire, and a battery connector
staples to hold wire down
nylon zip tie to hold lever down