I am just finishing up a wing tip locker in the left wing tip on my -6A. I will only place tie down ropes and the canopy cover in the wingtip.
For the 8 inch locker cover I fabricated it using the glass tip top skin that I cut out. I could not find an 8 inch hole saw bit to cut out the cover plate, so I spent some time and made my own. This allowed for a minimum saw kerf and looks pretty decent when closed.
For the hinge, I used the "hidden hinge" others use on the oil filler access door.
The last bit to finish is to attach a rib-type-thingy to the open end of the wing tip to absolutely keep anything inside the tip from migrating into the wing cavity
or aileron pivot.
I have two sets of wing tips, both attach using the "piano hinge method". The first set are painted and work just fine. The second set, in addition to the required nav/strobe lights, also is wired for pirotechnic smoke brackets and cartridges that I use with a local formation team. It is this second set of wing tips that I am using for the locker. Once finished, I will paint them.
I have thought about taking pictures and writing up a short description and sending it to KITPLANES. Maybe they will publish the article.