Im working n a terrax kit atm and ran into a major bubble problem on his leg. Well it was more of a super packed air pocket. When i drilled into his joint to create a pin to attach to his body, i almost drilled thru the leg.
So in my picture you can see the red area, that was the size of the air pocket in his leg. Before i sorta poped it with my drill, the leg felt solid, but once i poped it, there was like skin there that was left. If you look closely you can see the apoxie sculpt green tint on the leg. That is filled in with tons of apoxie.
So what i did was drill out holes in the flat areas, then pushed apoixe sculpt into the air pocket. As it dried, it sorta pushed itself out of those holes which i had to sand later. So what you can do is drill up a tiny hil or two, and push in apoxie sculpt to fill it up as best as possible without having to creat a huge hold in the sculpt.
Now when i say this was a major airpocket, think of your bone, without any blood or muscles, and just skin. Thats how big this air pocket was, and even funnier how solid the leg felt before i popped it.