These are jigs to help fold model tarpaulin sheets for the 7mm:1ft model of the coil cradles. They are unfortunately rather expensive in any plastic so you may prefer to do without or make your own from card or wood. Carefully separate them from the sprue and clean up the attachment points. Fold a suitably sized sheet of plastic of some kind over each one, as neatly as you can, and glue the overlaps in the sheet without gluing the sheet to the former.