Havent seen anyone mention this but if you do 15mm miniatures on washers in the USA read on.
I am building several 15mm fantasy armies, and I am basing on washers. most on 5/8 fender washers plus some goblins and such on 1/2" washers. Fairly recently, I orders some "custum" movement trays from britain ( I live states side) from warbases.co.uk
I had written them a email because they had sabot bases for using their money (pennies ect which are magnetic) and asked if they could do some for the 1/2", 5/8" and 3/4" washers we have in the USA, (because they havent debased our currency quite as much as in the UK).
I also asked them if they could offset there magnetic holes so they would not be in the center where the washer hole is, they also told me of a option to have a 1mm toplayer instead of the 2mm top layer ) there one layer is not mdf though, I think a card stock, but is seems good to me. I order a sampling to match the different washers sizes using both the 1mm and 2mm tops layers in both the "zombie" and regiment trays.
They told me they did such stuff for many people and they promptly emailed me back the prices for the movement trays I wanted. ( the prices were basicly the same as there standard trays meant for british currency, but get a quote from them anyways.
I ordered both there regiment trays and "zombie" trays. About a week and a half later, I received them in the mail. and was very happy with what I received. There prices are much cheaper then Litko ( whom I havent ordered from because of their high prices) (not sure why I can get packages faster from oversea faster then I can get things sent from state side… arg!!)
The standard USA fender washers fit great in the warbases movement trays, ( I wanted to test this out before I ordered more) (not to worry, the fit is great using standard Hillman fender washers from Ace hardware). I like the 1mm toplayer for the 1/2" ( size 10 as I cant find 1/2" fenderwashers with small holes) washers and their normal top 2mm top for the 5/8 and 3/4 " and larger washers.
Note, they will also do these for 7/8" and 1" and probably just about any other size washer also.
I will soon be figuring out what I need and making another order.