Sheet Styrene Cutters

Don't have one, or every had a need, but micro mark shows the "duplicate-it". Accepts up to 8" width, you can set up for repetive cuts.  Says up to 5/32" thick material.  Still uses knife or razor blades.  #84047,  30 bucks

They also show several miter cutters.

I usually get an order delivered in a week to ten days.

The Chopper can be helpful

https://nwsl.com/products/the-chopper

I'm using an MRP MRP-SC2 scriber and steel ruler now.  Better than any scriber I have used before and it did an excellent job with the precise, fairly complex shapes I needed to cut from .030 styrene to make side panel backers for my Su-25M1 project.  No overshooting on cuts either.

Hi-HooYah!

     You're gonna think I am nuts! How thick are we talking? The reason I ask about the thickness, I have found a tool that works for me. It is no bigger than a "chopper" tool from Short Line. It is a small little cutter. Now this is where it gets weird. You remember the big Guillotine blade, paper cutters from businesses and schools?

     Well this is a junior version. It even has a little drawer underneath for replicated parts. It will cut up to .030 thickness. Any thicker and it starts to wander. Remember this is for the home crafter though. You know, like paper flowers and stuff like that.

    It works incredibly well for any small cuts below 4"x6". I have been using mine to cut the small constructs out on the paper models so the lines are straight! It does work well for thinner plastic for maritime scratchbuilding too.

      Be warned though. I use edged triangles and clamps for thicker stuff. I have what I call a " Hook" I made from a carpet knife for thicker stuff. The old hook is getting up in years though. I bought a new one and am just now getting the blade shaped where I need it to be. Then Grinding, shaping and stropping with a lot of " Jewelers Rouge" On leather!

      I find most of the commercially made products a little bit less than what I need. Last thing you want when making showcases, even out of styrene as thin and brittle as C.D. cases is a weak blade that twists and wanders. So, go for the original suggestion. and I think you will be glad. I got mine at Micheal's. I think H.L. and Joann's carries them too.

Depends on what you mean by square.  Do you mean within the plane of the styrene, or out of plane?  For in the plane, i.e. square corners, for short cuts I use the square edge of the machinist square.  For keeping the blade vertical I draw the line first with a pencil or scriber, and use a thicker piece of stock to hold knife vertical.  For long in-plane cuts again I lay out line witih a ruler and cut along a heavy straightedge.

I probably should have posted this picture earlier.

My standard for cutting sheet styrene is the steel scale and X-acto blade. I have this other cutter for photo paper when I'm doing my photography and framing. I guess that I assumed with all of the other ingenious tools out there, someone would have come up with a styrene cutter like my paper cutter by now. I just started getting the Micro Mark catalog, but had yet to dig through it.

Thank you all for the suggestions and thoughts, it is much appreciated.

Micromark sells a good quality machinists square with the handle or base having two different offset thicknesses which help to align it better with different thickness sheets.