Did I just pull off a bonehead move....I covered a Sterling Skylark wing with silk, even went as far as 5 coats of Sig clear, looks great, and then realized I didn't put in any right wing weight or a weight box. Duh.....I'm an idiot....I can't see cutting a hole in the silk to add the weight, since my last attempt at patching silk on my Thunderbird looks like pure hell. I guess there is nothing else I can do. I even thought about trying vel-cro stuck on the bottom with 1/2 oz. of lead, but that doesn't seem very safe. I'd hate to see someone get hit if the weight came off. Any ideas???

I can't see how anything you could scab on to the outside of the thing would look better than a patch.  Maybe you just need to bite the bullet, cut into all that nice work, build your weight box and patch it up?

Could you put a weight box way out at the tip, where there is (I hope) some solid balsa?

Could you cut a rectangular hole into the silk at the intersection of the bottom spar and the outboard-est rib, then build a weight box up to the back of the hole?  I.e. build it inside out so that when you're done it's what you would have if you'd done it that way from the start?

You could always duct-tape some solder on after you get the plane all finished, and try to convince people that you meant to do that...

 Another vote for cutting and patching. Unfinished junk stuck on the outside will just make it look like an R/C plane.

 I say just go ahead and fix it right, any of the cosmetic issues will be on the bottom anyway. Enough repetitive clearcoats and sanding on the repaired area and you should be able to get it looking pretty decent. Patience.

The more obvious solution is;  drill a 1/4" hole in the L.E., near the wingtip.  Epoxy a 3-4" aluminum tube (with one end crimped shut) allowing about 1/8" sticking out.  Fill the tube with b-b's (from your 12ga. shotgun shell) and plug with a balsa stopper.  No need to disturb the silk covering!

Floyd

Model I am working on has the opening for the weight box on top of the wing rather than on the bottom.  I'll have to figure out how to make it look like I did it on purpose. 

I like the idea Floyd Carter came up with... going to drill the hole in the outer leading edge at the wingtip. It will be a lot easier to repair a 1/4" hole if I cover the end, or I may put a plug the fits tight in the tube. Thanks Floyd....I would never have thought of that!! 
I can't visualize a thing, but I can sure copy other peoples ideas!  Thanks again.

I would cut the silk and put in a weight box. As has been said, you will find that silk, unlike silkspan, will not wrinkle around the hole you cut. If you just want to add weight, go ahead and cut the silk enough to get some weight glued in, and recover the hole, and then cover that with a decal. I keep lots of decals of different sizes, to patch things. Sometimes easier than patching doped silk.