Or weld / bend up steel plate to make a crude square deck, that's what the decks on old rough cut mowers are and they do have advantages, I had an old hayter hayterette 4hp and that could cut stuff on his lover that stalled the more conventional mowers sporting the same engines, you loose a lot of power to the close clearance of mulching mowers, fine if you keep on top of the grass but if like me you leave cutting the grass in the back garden to a fortnight ago then having massive blade to deck clearance is a great idea, if however you have a collection box on the mower the mulching deck does save emptying so often. I 've 're made mower decks for one or 2 of my mowers, being tight I repair old ones that others think are past it, ready to sell on once 're painted.