As Dave says, McMaster is a great supplier. I got a 5-yard roll (the smallest quantity) of the 6" tape from them, and I think I got the medium-thickness version so it was about $36. That is enough to do both the ceiling inside and the roof outside - 4 feet won't be enough for either.
As I recall, I used the 3" tape on the ceiling of my earlier TM, and it wasn't quite wide enough. The movement of the shells caused the seals to scrub a bit beyond the edges of the tape. The 6" tape prevents this, and is a bit more forgiving in terms of placement. This stuff is really sticky, so if you don't get it in exactly the right place on the first try, you can't move it. On the other hand, I think TM uses 3" tape on the roof, so if you are really careful about placement, you will probably be OK. As I mentioned earlier, it really helps to have two people when you are installing it.
The color on mine is translucent, kind of like Scotch Magic Mending tape, and so it matches very well. The stuff that TM uses on the outside is opaque white, like Dave described, and quite a bit thicker than the McMaster stuff. I have no idea what they would charge you for a length of it.
Bill
|