I decided I wanted a roof socket, but the plastic is very thin there (made thinner by a heating vent or something on the inside of the roof). So I used some Apoxie Clay to thicken it up before drilling the hole on a second BB I found. I drilled it slightly under 5mm, then carefully used a grinding head to widen it until the bazooka fit snugly. I considered just making this Goldbug, but some of the painted bits scrape during transformation, so I left it alone. I just painted the putty bit to more or less match the window plastic.