If you get desperate you can make one with the lip. At Laitchs request I did one with a kickback. With a bit of trial and error a few buckets, and a heat gun and a round bar for a former I think a passable copy could be made, especially since you have one to copy. Failing that we have a business locally that molds and shapes Perspex to a high standard and he could probably do it. So try to find one that does it, they must be around.
Regards Martin.