I need a solid stand for the speakers bass to perform at it's best, so I set to on a mould for a cast concrete plinth.
The base board is melamine faced chip board, I sat the speaker on the board and drew round it with an indelible pen. The guide lines for the wood shuttering were drawn parallel to this with a slight increase in overall dimensions to allow for 12mm chamfered top edges. The face contacting the board will be the top one of the plinth, the centres for the threaded inserts are marked out and the circle in the centre will have a disc stuck to it, creating a pocket for the spirit bubble to sit in.