I made a foam rib to help stiffen the flimsy Wing Tip.  A few RVer's said they have seen the top of the tips

collapse during flight.  The 2 holes are for access to the back side of the tips to mount the LED Nav Lights.

I actually placed it on a diagonal to keep it centered within the tip fore and aft.  I marked the location and sanded where

it will be Epoxied into place.   Also you can see here I ran out of #6 plate nuts.  If you decide to attach your tips with

screws, get ready for installing about 68 plate nuts for this convenience.

I mixed up Epoxy with glass beads and glued the rib into place.