How are your clay-modelling skills?

Why not try to use an epoxy modelling putty? ‘Milliput’ is the best thing I’ve used; it is easy to work with (after a bit of practice), is quick-drying, can be drilled, sanded, machined and painted when dry, and is also relatively cheap.

You could use copper central-heating pipe to give the form of the ‘spade-grip’, the 10mm stuff will easily take that sort of bend by hand, and then you could mould the epoxy-putty around it to form the bosses for the control column and for the firing button. You wouldn’t need to be too accurate as you can file and sand the putty to the correct shape and you can always add more where you need it, plus much of the surface could be covered by ‘string’ grip. Any wiring, and even the firing button, could be embedded directly into the putty.

It would take time and patience but if you made a good job of it you could always sell a couple more on eBay!