The spindle route is the one I thought I’d be going down, based on your suggestions.
However, they are not a cheap option compared to the knock-off Katsu Makita clone, which is very well reviewed and only £36. The other attraction is that it’s more versatile and there’s no need to house the separate power supply.
After posting, I went ahead and finally ordered one, so I’ll be in a position to give feedback soon-ish. I still need to build the thing, but I’ve printed all the parts and have the bearings from China. I can get all the hardware and conduit in a shop over here called Screwfix.