I am building a ceramic shower stall from scrach. We are instaling a custom made glass door . My question is when I am buiding the threshold under the door should it have a slight slope to the inside. It is going to be aprox 4" wide. Also should the threshlold be made by stacking 2x4s or should they be put on edge?

It would drain the water off the door into the shower if it had a slight slope to the inside but I would think a very small one.
The threshold should be made sturdy as possible, I think I would lay the 2X4's on edge. And I would make sure that the complete threshold be covered in what ever you are going to use as a pan for the shower. I have never seen a glass bottom in a shower and I am not sure what kind of drain it will have but I am sure what ever it is it will need to be what is called a double seepage drain. This is so that any water that got behind the tile or under the glass will drain off into the secondary drain.

I am building a ceramic shower stall from scrach. we are instaling a custom made glass door . my question is when i am buiding the threshold under the door should it have a slight slope to the inside. it is going to be aprox 4" wide. also should the threshlold be made by stacking 2x4s or should they be put on edge?
Consider also using a Ferro or Wonderboard surfacing face for the final tile setting surface. The scratch coat can be a thinset Quickrete for smoothing out the overall surfaces and fine edge work before putting down a mastic sealer/adhesive coat. After that is done, then a buttered tile set into the base mastic coat will not require additional sealing other than the grouting with a finish sealer. The Ferro board over flat 2x4's will be adequare enough to support the threshold into the shower. Just a thought. nmwirez