I think I'd bolt it to a piece of metal sandwiched between two bits of wood, the top one to look pretty and the bottom one with cut outs for the nuts. Then you just need to get hold of some bolts which can be cut down in length.
Do you actually want to be able to sit on it? I think the base would need to be quite big to be stable.
Hmm, good idea, I had considered two bits of wood, but not the metal sandwich. Yeah, ideally it could be sat on (probably not regularly, but ideally possible!). And yes, I fear the base is going to have to be quite long to make that possible! Fiddly!
I think I'd bolt it to a piece of metal sandwiched between two bits of wood, the top one to look pretty and the bottom one with cut outs for the nuts. Then you just need to get hold of some bolts which can be cut down in length.
Do you actually want to be able to sit on it? I think the base would need to be quite big to be stable.