I designed these bases for infantry battalia in For King and Parliament. The three larger bases each take up to a dozen 28mm minis, the command base takes five or six.

They are cut from 2mm MDF; 3mm diameter magnets (sold separately) can be fitted into the holes to secure them in storage or transport. The edges of the bases can be chamfered with a craft knife and the naturalistic appearance of the wobbly edges helps them to merge into the playing surface. 

This pack includes four bases, making a unit 25cm wide (the unit size that Simon uses on a 30cm grid): the bases are approximately 85mm wide and either 70mm (FK&P1) or 50mm (FK&P3) deep. The command stand can be placed in front (as in the attached photo) or behind.