I was recently asked about a homemade photopolymer base I use at The Arm and thought it would be of value to post the reply here where it might be of use to others.
“The base you saw at The Arm was an acrylic base with an aluminum surface laminated to it. It works okay, but I must say I really prefer the Boxcar bases we have here. That homemade base doesn’t have the dimensional consistency of their bases. If you can’t afford that Boxcar and are willing to do a bit of work you can also get some plate aluminum from these guys http://stores.ebay.com/FORTAL-Aluminum and then have a good machine shop mill it down to the appropriate base thickness for the photopolymer plate stock you intend to use.
Machinists are often only able to mill to a consistent thickness over a small area so you could take more than one piece of material, have it machined down to your base thickness and puzzle it together on the bed of the press. I personally think it is better to have a base that is in multiple pieces so that you can later decide to use only part of it. This allows you to lock up type with photopolymer and not have to run the same color through the press twice because the plate base has gobbled up too much of the bed.
You won’t get the nice anodized grid as provided on the Boxcar bases, but at least you’ll be printing!”
The Arm Letterpress