in reply to chris, just seen your question, the mines are available in resin from a few firms germany and one from down under, but the cost, well put two on the boat, and you could buy another boat, i made mine from wooden balls you should fine in any good craft store, need to be 31mm dia, well give or take a 1mm, as the real ones on mine were 44inchs in dia, the horns are cocktail sticks with point filed down, and few washers, the trolley were made from kinder egg toys, but if make the square block type you can use balsa or plastic card, not counting buying the kinder egg chocalate, i have built three mines so far at cost of around £2.oo, hell a lot cheaper than the resin, o.k the resin might have bit more detail, but i am happy with them, and its a laugh down at the lake when people ask, wooden balls and cocktail sticks, i will dig some close up pics of them, and post them