I didnt take pictures and dont want to take it apart unless it breaks, it's glued together with seal all lol.
The end result looks like the ebay link above.
I cut the stock intake off a 1/4 inch from the flange on the cylinder side, jammed a metal broom handle in it then slide a piece of rubber hose over it and coated it with seal all. This is 7/8 inch outer dia and sits flush with the carb holder.
The key to making an intake and fitting the 372 carb is boring the carb holder plate to 7/8 inch and mounting the carb flush to it. The 372 carb wont even open up on the stock intake and it's longer so you need to make the intake shorter so the air filter fits under the cover.
I have built a metal intake too, it was on a supmix 6200, again it looks like the one above. This was easy, weld a piece of 7/8 inch od pipe to the stock intake flange that will sit flush with the carb holder. I think the intake was 19-20mm total length. It seamed to work fine but it may cause hot start issues on a hot day.
I recommend buying one, it's pretty cheap, making one is a pita, it takes a couple hours of test fitting it to get it just right.