You will see them on my next T-Bolt. Much stronger and lighter..

Ty,

Epoxy fillets, without even some 'dust' (microballoons or whatever) CAN be painted and not lift.

First to suggest this, I think, was Dee Rice, in the MAN Oriental article. Basically, 5-minute epoxy smoothed on with fingertip or prop tip...

For the amount used, negligible weight gain. To keep it paintable, nitrate dope dusted-over per Joe Reinhardt's FM Gypsy 35 article... Just overspray to build color coats and butyrate color.

Mask? yeah. and some high% rubbing alcohol to feather the edges. Use the high% rubbing isopropyl to kill finger oils if you, like me, can't resist touching the fillets with oily fingers.

Sanded balsa fillets with a wipe of 5-minute are even lighter and larger... Going around tight turns may require cutting a 'glove' of soft balsa to the curve... No matter - even 5-minute will saturate well enough. When all this under-stuff looks right, a thinly stretched scrape of 5-minute finish-preps the fillet for final finishing.

Ty, if I can do it, you sure can.

The leather fillets I use are very soft.  I pre-glue the area the fillets will "fill" and then using a lot of Ambroid I lay the precut fillet into the joint. I use a ball on a stick to force them into the groove so to speak.  They come out very smooth and no edge. They lay right down. On  occasion I have wet an area with thinner and relaid it. Then after they dry, I coat them with Ambroid.  Later I dope and sand them. I do the fillets AFTER the wing is covered.  There is a warehouse that sells them in one hundred foot batches.  That's where everyone gets them. No kidding.
The ball on a stick is a device I obtained through Micro Mark that is used to smack a drilled hole to make it a little smaller.

You are correct, Sir!

For the "ball on a stick", I just glued a ball on a stick with J.B. Weld. 

Bill <><

Yes a marble will work.  You can also use steel ball bearings.  The size depends on the radius of the fillet.  Ive used popcicle sticks too, which can be bought at a crafts store.  But, the ball on a stick give a more consistant radius.

Thomas

Why Ambroid glue? Ron.

It's light, sands well, It's light, and dope sticks to it really good!  Did I say it's light??

Bill <><

And it makes my jeans stand up in the corner all by themselves!

Just use your wing rib pattern to cut fillets out of scrap balsa.