I'm still sanding... (yeah yeah yeah)

Last post I mentioned I enjoyed the sanding of the hull, but that's over now. Sanding this hull is a lot of work, and because of all the concave curves not as easy as the float hulls.
It's nearly done now, luckily. Yesterday I sprayed some high build epoxy primer on the hull.
For the primer I'm using this 'HVLP' paint sprayer for home use. It's probably not good enough to spray the final layer of paint, but for primer it works ok.
After that it's sanding time again, this time not by hand but with an electric sander. The primer is rock hard and sanding it shows imperfections much better than when sanding the relatively soft/coarse fairing compound. I started sanding a part of the hull and it seems I have to sand off a lot of the primer (+ guide coat) to get rid of all the scrathes and other imperfections. I'll sand with grit 80 and after that spray another coat of primer which I will eventually sand with a much finer grit.
When I get tired of sanding I try to work on some other parts. For instance on the slides for the hatch. Using real jib track + slides for the hatch would be very expensive so I decided to try to make it a bit cheaper. Since the slides will only have to bear the weight of the hatch itself, I thought the slides needn't be superstrong. I made a track by sawing a groove in a 2*1 cm aluminium profile. Then I made slides from a thick polyethyleen (HDPE) cutting board.
It's easy to make the tracks&slides if you've got a table saw with adjustable depth of the saw-cut. I think sawing aluminium with a good wood-sawblade won't hurt the blade too much, but to be sure I used an old damaged saw blade (hit some screws with it earlier on).
By cutting the grooves in the slides not at the same height, I angled the sliding track 7 degrees as per plans. I'll glue the tracks to the hatch with epoxy fillets, so I won't need to bother with HD inserts and screws.
Tomorrow I'm going on vacation for two weeks, after that I hope I can get the building up to speed a bit again. Still trying to finish the boat before next summer.