I was in a fit of nerd glee the first time I used tooling board. I’d used MDF for similar purposes before, and I doubt I ever will again. Called Renshape, Precision Board Plus, or that green stuff people on another continent buy; it’s all the same extremely useful, unfortunately expensive, stuff. It’s hard to pin down exactly what tooling board is. Most of the blends are proprietary. It is usually a very dense polyurethane foam, sometimes by itself, sometimes with a fine fiber filler.

What makes tooling board so good is its absolute dimensional stability and its general apathy to normal temperature swings. (It even comes in versions that can go through curing ovens.) It is impervious to humidity. It has good surface finish, and it machines perfectly without wearing down tools.

This stuff is really tops as far as machining goes. I got super precise molds out of a very basic CNC machine at the LVL1 hackerspace. Renshape cut easily at a high spindle speed, and put practically no load on the machine. Climb and conventional milling were equal load wise with no immediately perceivable difference in finish. In the end I hit the precision range of my cheap digital calipers: +-.005mm, when the temperature is right, the battery is a charged, and the planets align.

I like to do resin casting when I get serious about a part. If you are making a master mold, there’s nothing better than tooling board. I’ve used both Renshape 460 and Precision Board Plus. Both impart a very light matte pattern, equivalent to a light bead blast on an injection mold. There’s no finishing required, though I mistakenly bought Renshape 440 at first and had to sand it a little to get the finish I wanted.

Tooling board is great for masters in metal casting, and is often used in the industry for just that, especially if quick and accurate prototypes are needed. It’s also tough enough to last through a few rounds of metal stamping in the home shop.

If you are doing lay-up for carbon fiber, fiberglass, or leather, this is also a very good choice. It will be unaffected by the chemicals, heat, and vacuum you may use in the process. It is tough enough hold alignment pins for proper set-up without premature ovaling. It is also a very good choice for vacuum forming.

Tooling board is, unsurprisingly, really good for tooling. It’s a great material for soft-jaws, alignment fixtures, and assembly fixtures, especially if you are doing delicate precision assemblies.

If you’re made of money, tooling board can be used for models, signs and props. It sands, shapes, and files extremely well. It bonds well to a lot of substances. It also takes paint very well with none of the absorption properties of wood or MDF. Most professional model shops will use it.
The one big flaw of tooling board is its price — this stuff is expensive. There’s no good DIY version that I’ve scrounged up so far. If you’re making a mold master, a fixture, or anything where you need tooling board’s properties and you are likely to get a few uses out of the board, then it’s probably worth it. Also, be careful of sellers selling plain “Renshape” it is probably going to be the lower grade Renshape 440 and not the more expensive Renshape 460 (or equivalent), where you start to really see the surface finish advantage of the material.

Tooling board is an industrial material. Typically you can call up a supplier and tell them what you’d like to do with it and they will be able to help. If you are making tools for carbon fiber quadcopter frame lay-up, let them know and they’ll have a formulation for that. If you are resin casting, there’s a formulation that gives superior surface finish.

It’s a pretty common material in the industrial scene, but I don’t see it a lot on the hobby scene. This is almost certainly due to its cost, as well as a shortage of small quantity re-sellers. (If someone starts selling assorted sizes on eBay for a reasonable price you have at least one buyer in me.) However, after using it in the niches it is designed for, I really don’t use anything else. I used to hack MDF to fit, but MDF is awful to paint, has no dimensional stability, and dulls tools really fast.

Are you a fan of tooling board? Have a good source? If you have anything to add, let us know in the comments.