I know lexan and plexi aren't the same, but I need one of them for a small project (holding a parking pass that I transfer between vehicles, a bicycle, and my backpack) and I'll purchase whichever I can find cheapest.
I'll be using 1/8th or 1/4" thick and just cutting out a small recess to hold the pass.
To make things interesting, and because I don't have a "real" router yet, I'll be using a dremel with a 1/4" straight router bit...
Any retrogradations for the speed to run it at so I don't melt plastic and wreck the bit (granted, it's only $8, but I'm cheap)

Hopefully in a few more weeks I'll have a bit more $$ saved up and I'll make up my mind on a starter router.

Your problem is challenging. The biggest problem you will confront is the plastic melting as you cut. For real routers there are dedicated O-flute router bits but as far as I know they are only straight non-plunging bits. However, the wood-cutting bits can also be used if the right speeds are chosen. You will simply have to try in order to find the best speed of rotation (rpm) and the best speed of feed that allows cutting without melting.
Lexan v. plexi. Lexan has much greater mechanical strength than plexi; NASCAR windshields are lexan, and Formula 1 is considering requiring that their cars have windshields of lexan. On the other hand, plexi has much better chemical resistance.I have not been able to check which is less expensive at this time. There are several online stores that sell each.
Good luck. Keep us posted on your progress.

Hi Bill, lexan also has a lower melting point but is virtually unbreakable. Not sure how large a piece(s) you need, it is available on eBay in various sizes. Mostly cutoffs from sign making or display mfg businesses. If you have one in your area you may be able to do some dumpster diving for what you need.
I wonder if you are going to get what you expect though. Routing the stuff will remove the surface polish and, unless you have a means or knowledge of how to polish the stuff, it will leave a hazy/milky appearance where it's been routed. Picture is a shot of a zero clearance dado insert I made for my table saw. The hazy areas are where I had to relieve the bottom to provide clearance for the arbor bearing and riving knife bracket. Material was 3/8 Macrolon (lexan with scratch resistant coating).

You may have better luck using two pieces of thinner material glued at the edges.

Just some suggestions

Attached Thumbnails

I checked at my local big box and they have 8X10 sheets of lexan for about $5. I'm going to run down to my local Ace in a bit to see if they have anything and peruse their reconditioned tools for good luck. I've helped my dad bend/mold lexan in the past. He got tired of the sand and salt in the trucks getting wet and freezing so we made some tarp supports out of some rather large pieces of lexan he had laying around. You can do amazing things with lexan and a heat gun (don't use a torch, it scorches easily...)

I hadn't thought of the polish and haze. I'll have to poke around online or just buy a piece of lexan and see what happens. If I'm out $5 or less, I can happily chalk that up to play and education.

I picked up a 9x16x1/4 piece of acrylic at ce for $3 . I'm anxious to see what happens tomorrow. higher melting. point but more brittle...

You're too hot when bubbles form in the material. I would suggest using the thinnest possible material

When I cut either material, I leave the paper on for the cut. I don't know how or why, but the paper seems to dissipate the heat and I get less melting.

It's possible to "flame polish" the edges of some types of plastic. You just use a propane torch passed quickly along the edge. Google for more info. I've done it, but it's been years and I don't trust my memory on the subject to give more advice.

I use a lot of Lexan for my routing templates. Why not make a template and rout the actual card holders. You can saw and file the template and leave square corners if you don't rout it. Drill out the waste, scroll/jigsaw to line and file up to size. When you do rout, be prepared for Lexan flakes everywhere.

As I recall, many plastics will "polish" with a light rub of acetone.