Polystyrene seed trays (Norbiton KT1)

After a community gardening project, I find myself with a lot of expanded polystyrene seed trays. 26 x 16 x 6 cm with 6 individual slots each 7 x 6 x 5 cm. All used. 11 are intact, 5 have the holes in the base punched through - the photograph shows one of the worst. All potentially useful to gardeners raising from seed, but I do not have room to store this many.