The best way to stick correx together is with a polypropylene-friendly hot melt glue like Tecbond 261. It sticks admirably well, but supposedly won't stand up to prolonged exposure to wet. Fine for a racing season or two.
When anchoring correx with cable-ties, it helps to double layer with the corrugations at right-angles, so it doesn't pull through.
I molished wheel covers for the Baron using 1mm ABS. Easy to cut a perfect circle by drilling a central hole, and bolting a Mk 1 bit of wood in place with a scalpel blade attached at the right radius. Probably viable with correx too. The problem I found was that you have to split the circle to get the dish right, then anchor it in place on the wheel. I tried to be clever by gaffer-taping it in place then removing it from the wheel and solvent-welding a strip of ABS across the seam, but this just made for a lump of stiffer material that stuck out. Attaching to the spokes with cable ties seems like a good idea, but unless done very loosely tends to result in warping. I found that insulating tape to the rim's braking surface gave the best results. But not as good as some sort of heat-shrink plastic (think model aircraft wings) that other riders have used.
Disc brake calipers and derailleurs need more clearance than you think they will. I had to swap the BB7 on the front back to a nasty Shimano caliper to gain a bit more clearance for the disc, and bottom gear at the back (which you don't need for racing) makes godawful rubbing noises.