I wanted to use aluminum for this project, 10mm thick would have done the job but I had no idea where to souurce that size sheet from; however, I did have some sheets of 25 mm Delrin so I thought I'd have a bit of a play with that medium.
Delrin turns nicely giving a nice finish, but when grinding and filing the finish is quite rough. I expect some more work in this area to neaten the project up a little.
I cut a rough shape from a largish slab and set about shaping it with a finger file. The hole for the motor was turned on the lathe, this necessitated making the handle a little shorter than I'd like. As it turned out the handle fits the hand quite comfortably. I cut a slot just forward of the handle and tapped a hole from the top of the blank for clamping the motor in place. Next I mounted a small piece of Delrin in the four jaw and drilled a 10mm hole for the front wheel mount. After mounting the motor, I spun up a small piece of Delrin and sunk it into the drive drum and pushed the drum on the splined motor shaft. I was going to use some Delrin for the drum but thought it might melt so used a stell drum mounted on a Delrin Bush.
For the motor cover I turned a 12 mm thick piece of Delrin to fit over the motor and then turned down a piece of PVC to slide over that. The end is capped with another piece of Delrin I had lying about, yellow unfortunately. I mounted the swich in that.
The unit works nicely, but curiously the 18 volt motor I sourced from an old cordless impact driver smokes badly when run on 18 volts. On 12 volts it runs ok, if a little hot.