There's several ways to cut circles.

For large cirlcles, there's several types of compass-cutters, I refer to the above.


It can be ordered from Micro-Mark for 19.95 USD but if you're a bit handy, many student-type compass can be converted to a circle cutter, if they do not already provide a tool to insert pens or pencils (read : "X-acto knives !).


To make small cirlcles / discs, there's several options.

1) a hole-punching device[b] like used to make shoe-string holes or holes in a leather belt.


You can order it from www.micromark.com for 16.95 USD

2) b]Use a punch & die set



Like the picture shows, such set allows you to drive a metal chisel of the exact size (enclosed with the punch and die set) through the plastic sheet into a metal frame that has the exact same diameter. The result is a neat round hole in the plastic, and a nice round plastic disc/cirlcle. Ideal to make washers, rivets, bolts, etc.

Two companies supply Punch & Die sets : Historex (UK) and Waldron (US).

Waldron's sets come in two sizes, one with larger holes than the other.
Historex"s set comes in two sizes, too. One with round holes (overlapping bothe sizes of both Waldron's sets) and one with hexagonal holes.
Though this is not the subject of this posts, i just LOVE the hex nut set. It makes perfect little bolts. If you're a bit of a scratchbuilder, this is a must have, just as much as a round punch & die set.

To my opinion - shared in several scratchbuilders - Historex is the best buy.
You can find more information on http://www.historex-agents.co.uk. Scroll down to the bottom of that page to "Help with Punch and Die Sets".

Both sets are hard to find in retail, but can be ordered through mail or the internet.

To be complete, here's waldron's address, too :

Waldron Model Products
P.O. Box 431
Merlin, OR 97532 TD
US

3) make your own "punch set".
To make holes of diameters between 4 and 8 mm (too large for a punch & die set, too small for a compass), I use short pieces of assorted metal tubes. It works even better if you make the rim a bit thinner (sharper) with a diamond bur. The thinner the cutting edge, the nicer the cut.
You place the piece of polystyrene on a tough yet flexible surface (a nylon cutting mat works excellent) , place the sharpened piece on tube on top, and bang on it with a hammer.
Short pieces of tube work better than long ones. Try pieces of about one inch. That allows you to hold them without crushing your fingers, and it avoids that they bend when you hit them with the hammer, like longer pieces would.

Good luck !

:-) I also carry and havie in stock a new line of P&D. These are sturdier than any of the other sets I have used, and have a mor sloid support. I'll try to paste photos this week. There is a set of Hex, and a set of round. They retail at 70.00 Euros each. I'm not doing door to door here just informing. I also tried the Reheat type and they are very nice, but the smaller, mico sizes break easily. They are also very difficult to get a hold of! As usual the crow of the good ship Armorama.com receive 10% kudps.

Jack the merchant boy :-)