35" shower door acrylic dam / threshold 1/2" by 1/4"

Use 100% pure clear silicone chalk. After you fiqure out the correct length and position for the threshold place a strip of masking tape on both edges. This way when the chalk oozes out from under the strip it goes on the tape. After it dries pull off the tape and you have a super clean edge.  Also Very Hi-Bond Acrylic Adhesive Tape from crlaurence.com would work.

We can cut it to your size.