Hello Scott,
Here are the measurements for this dust cover. I've the lab-400 but this cover was made for all 400 series of TT. The only difference is on the attachment in the back. Mine has a pressure clip but others might have the insert and screw type attachment. Since they only made one cover for all, they incorporated this type of attachment, although I personally don't use it. I will give you also the dimensions on the screws type attachment, just in case yours has this type.
All dimensions are taken from the inside, so when somebody makes this cover, he can make it as thick as you want. The bottom is slightly wider than the top of the cover, less than 1% difference, so a very slight angle from bottom to top.
Here are the dimensions...
Width 16" and 13/16"
Depth 13" and 1/8"
Height 2" and 5/8" The height can be made bigger if you want, but the measurement are of the correct required dimensions.
Now for the square attachment in the back...
The width of it is 1" and 7/8"
From the corner to the start of the attachment, 1" and 7/16"
From the corner to the end of it... 3" and 1/4"
The height is 1" and 1/16"
The width of the little opening inside the attachment is, 5/8"
The distance between the two holes, from centre to centre is, 1"
Need any more info, just ask.
Hope this help.
Regards
The cover has a sort of light amber color, sort of a shade of dusk.