what/were this ply?

Looks like Baltic Birch. HD can special order it if you go down to the Pro Desk. Rather expensive though.

And you’re right, it is great for jigs.

If you’re willing to pay even more, look into phonellic (sp?) coated plywood. One brand is “Finform”. Absolutely wonderful for jigs. A sheet of 3/4” Finform will probably run over $100. If you have an RSC Rental place in your area, you can try there. They carry it for rental by contractors that use it to shore up trenches and excavations. If you pick through their stock, you can often find a good sheet or two. I’ve bought them used for around $75.

The phonellic resin coating on both faces makes it a very smooth surface that does not require any finish and it is fairly resistant to abrasion. The core of the Finform is Baltic Birch.

-- Dave; Lansing, Kansas

Thanks firehouse. Looks like woodcraft carries both of those. Will check it out. cheers.

-- William, Brighton, MI

i get it at menards right off the shelf ;)

-- if you dont have it, build it, especially when its a stupid idea