Using a horizontal mold, you can create single pen blanks or a block of resin that can be cut to size.
There are a few vendors that make horizontal molds for both block and single blanks. Fred Wissen
(http://www.ptownsubbie.com/) has very nice molds that are made of a flexible rubber. I think it is a silicone based compound.
Then you have the plastic type molds made by Castin’ Craft. They are block molds that are: MC7: 8
ounce RECTANGLE - 3" x 5" x 1-1/16" and, MC8: 9 ounce - RECTANGLE - 3" x 6" x 1-1/16". These are two that I have used in the past. They work better if you use a release agent.
Making your own mold is very easy. There are several methods that give you good results. I’ll start first with the cutting board mold. Using a plastic cutting board from one of the big box stores, you can cut
it into strips. By screwing the different parts together to form a rectangle mold, you can pull apart the mold
when the resin is cured by remove the screws and dissembling the mold. You can find good examples and even a cut list with a Google search of cutting board molds.
Next methods would be making a mold from 100% acid cured silicone sealant. You can buy the silicone
at your home improvements store. You can tell if it is the right material if it smells like vinegar. When I made a mold, I created a “positive mold’ form, cover it with saran wrap, squirt the silicone into a soapy
bucket of water to make it easy to handle, and formed the silicone into the positive mold. Sorry, I’m not
trying to provide building instructions, just give you the basics of the process.
I’m sure there are others but the last horizontal mold idea I have would be to create your own mold with silicone rubber. The link to my video is in the previous post.