There are different types of "plastic" pen blanks. They include (but are not limited to)
- Acrylic,
- Polyester,
- Urethane, and
- Epoxy
Unfortunately, many people mistakenly refer to all of them as "Acrylic", but that is a misnomer. It's analogous to calling all soft drinks "Coke". While Coca-Cola and Pepsi-Cola are both colas, Dr. Pepper, Mountain Dew, 7-Up, and Grape Nehi are very different sodas. You wouldn't be happy if you went into a restaurant, ordered "Coke", and got RedPop, would you? Likewise, we should be more careful with how we describe and advertise plastic pen blanks.
Berea Acrylic pen blanks are true acrylic (poly-methyl methacrylate a.k.a. PMMA).
Inlace Acrylester is not acrylic in any way, shape or form. It is a polyester resin.
RhinoPlastic blanks are advertised as acrylic, but I don't believe that is true. I suspect they are also polyester.
I have seen some members here pouring their own polyester resin blanks and selling them as "acrylic".
I've purchased and turned real acrylic blanks, and I pour my own (and sell some) made from clear polyester resin (Silmar 41), clear urethane resin (Alumilite Clear), and opaque urethane resins (Alumilite White and Alumilite RC3 Black). Each type has its own drilling, turning, and polishing characteristics.
Real acrylic (PMMA) blanks drill, turn, and polish easily. They are typically extruded (at our price point) and the manufacturing process is beyond most of us. I don't trust anybody who claims to make their own acrylic blanks.
Polyester (e.g. Castin' Craft, Silmar, and Polylite) resin blanks are fairly easy to make and well within the ability of a home turner. These are the resins that smell like Styrene and are hardened with MEKP. How easily they drill and turn is very dependent on how they were cast. When catalyzed properly, they are not difficult to use. When over-catalyzed, they can become quite brittle. I suspect that Inlace Acrylester blanks are over-catalyzed (which makes it quicker to manufacture, but harder to use). Polyester is generally easy to polish to a high shine.
Alumilite Clear is a two-part urethane resin that is easy to use (but must be measured by weight), doesn't smell bad, and produces blanks that are relatively easy to drill and turn, but can be difficult to polish. A high-gloss finish requires more attention and better technique. You must cast under pressure or you'll get tiny air bubbles in the blanks.
Alumilite White and RC3 Black are also two-part urethane resins that are easy to use but set very quickly. They are opaque so you can't color them with mica powder. You must use compatible dyes (and the dyes for PR are not compatible). Moisture will make urethane resins foam (clear or opaque), so you must avoid any water contamination. These blanks, however, are not brittle at all. They are very easy to drill, and the easiest material I've found to turn. If you are trying to learn how to use a skew chisel, get some Alumilite White or Black blanks. They'll make you feel like you know what you're doing. The white blanks are easy to polish. Black tends to show off the tiniest scratches, so it takes more effort and better technique.
There are many different epoxies - with different properties. Some members here use West System 105/207 with good results. I haven't tried it myself. It has a long open time (which means you don't have to rush when using it) and is very strong, but is more expensive than other options.
Whichever plastic you choose, I encourage you to use the correct terminology.
I hope that helps,
Eric
