"Three Green" Lead Clay - Nose Weight Uschi van der Rosten
Flexible lead putty that can be applied in tiniest quantities and hard to reach areas where traditional lead weights would be difficult if not impossible to place.
It's tacky so there is normally no need to glue it in place and it's mass to weight ratio is excellent so you won't need much space (or much product) to keep your the nose of your plane on the ground.
Even if you forget to put some weight into the fuselage Three Green can fit through the tiniest hole. You can drill a little hole in a hidden spot like nose gear shaft and plug the product right into it.