I want to add my kudos to Warbases, they do excellent work for low prices.
My figures are the same: 24mm washers (close, anyway) so I went with 25mm diameter holes in movement trays from warbases. Since the washers are metallic, my first thought was to get a magnet in there somehow. My first idea was for magnetic sheeting to be sandwiched between the two layers of the base. The guys at warbases suggested instead that they custom cut movement trays with a small central well for a round magnet, and they were asking me for the diameter of magnet I was planning to use.
After consulting with guys here and on TMP, I decided that I really didn't need magnets. And really, as long as you don't put the bases on a steep slope or shake them upside down, the minis stay put without magnets.
About depth: my washers are 1mm thick. Most of the figures have integral bases, which I try to cover up using sand, washes of paint, flocking (and tufts of grass for my lizardmen). That brings most of them very close to 2mm in depth.
Look closely at the bases in this post:
http://leadadventureforum.com/index.php?topic=80685.msg1001242#msg1001242No, they are not seamless. Yes, there is a minor depth issue. But I like the added solidity of the 2mm movement trays. No doubt you could get them to do a 1mm special order. But I suggest trying at least one standard 2mm base before deciding.
PS: feel free to comment on the Dragontooth minis and basing, on that thread over there, if you feel so inclined. <g>
Cheers, --- Phil the Dragontooth maven