how to attach BC platforms?

me and a mate are making a BC wheel. we have everything, but we not sure how to attach the platforms. Do we simply screw them really tight or do they have bearings or something?

They simply slide over the ends of the axle and are held on by the axle nuts, just like the frame would be in a bike. Just make sure u have them level before you do them up, as they don’t move realtive to each other once fixed. The bearings in the bike hub will handle the rotational side of things.