After success on my SkyRaider wings, chance to try slightly more complex overhead-folding, on one of most expendable kits in my stash:
Revell (nominally) "1:48" Cougar is what Garry would've called a "humble" kit - not even quite 48-scale, judging by comparison with the Monogram 1:48 Panther (not shown) - but overall shapes and proportions look decent, so useable for this trial.
Wings come already separated - and not even along fold lines - so first step was to glue them on:

Click on Image to EnlargeEntire, thick F9F wing roots molded into fuselage halves, so in addition to attaching wings (left, top), bottom center section was removed (left, bottom), to provide required access. Cutouts for lifting-arm insertions were transferred from Monogram Panther mold, presumed very similar if not identical, but further work along fold line would have to wait for "fully-cured" date, labelled with tape (bottom). At right, on undersides ridges along hinge axis could be flattened (top), and aluminum axle tubes cemented in (bottom) using CA-putty.
Two weeks later, progress could resume:

Click on Image to EnlargeAt left, lifting arms sculpted from solid blocks - again, just like on SkyRaider - except this time arms anchored inboard, as outboard wing too thin, and also at less than 90degrees, to follow sloping wing root (bottom). Conversely, wire ends now anchored on outboard wing (right), except complexity of trapping under plastic strips, done for portside wing (top and middle), was found to be not only redundant but an impediment. Outboard wing is so thin there is no room for the buildup, meanwhile the bottom wing pieces (not shown) will provide (more than) the same support. So on starboard installation (right, bottom), wire ends simply glued down with heavy CA-putty - that's the way to do it.
Wish I could report that at least the folding came off without a hitch, first time - but that was not at all the case. The thick wing-root of the F9F (Cougar or Panther) represent a hugely-exaggerated wing camber: more camber requiring longer clearances - greater clearance requiring longer lift-arms (though I don't yet have a way to predict/calculate this precisely).

Click on Image to EnlargeIncremental whittling-away of the fold joints on the first wing, until it opened (not shown), finally established the basis for success on the second wing (left, top) per the following:
Fold-joint line: 0.7" inboard of air dam on wing
Arm Length (same for both): 0.3"
Hinge Axis: midpoint under arms (0.55" inboard of air dam)
Note I maintained a perfectly straight-line fold joint. This may or may not be accurate - I really don't have sufficient references to know.
The next step is integrating the bottom wing pieces - already started for the port wing (right) - however when that fold-joint had to be re-established substantially further inboard, it became aparent that further progress would require the bottom wings be attached to the bottom cutout and their joints relocated inboard, as well:
Click on Image to EnlargeThus work came to rest in this state, to wait another (at least) two weeks, before restoration of the port wing, and completion of the undersides for both wings, can be addressed.
Meantime (out of impatience) I drilled out all the holes in the belly dive brake (right foreground). But - although I think it can look good with folded wings - it could take an almost unlimited amount of further detailing/correction, which I'm not sure would ever be worth the effort.
Still, I'll definitely keep you posted on the lower-wing installations, and final result.
Cheers,
-Matty