This movement tray is 2 layers of 3mm MDF. This tray holds holds 5, 20mm round bases. The spacing allows for models that overhang their bases and is configured so that multiple trays can be used to form a line or a other shapes more representing a mob. The spaces for the bases are slightly larger than 20mm to allow for any extra paint or material which may be on your model's bases.
We use a high quality MDF which will not warp with normal use and can be painted, primed and finished the same way you have based your models.