I tried this just the other day, it didn't work very well. The scrub was OK, but it disappeared too fast. All I can say is don't forget the wax...
I just took a scrub recipe that I liked and subbed out any liqiud oils with butters or oils that are solid at summertime room temp - shea butter, cocoa butter, palm kernel oil. I also used...hang on I'll just post the recipe. Bear in mind that it is a first draft and I'm not happy with it, but some ideas would be nice.
25% cocoa butter (solid at room temp)
7% palm kernel oil (solid at room temp)
4% shea butter (solid at room temp)
1% stearic acid (thickener)
1.5% emulsifying wax (I don't like really oily scrubs in the shower)
2.5% conditioning emulsifyer (as above)
7% SLSA (I like some foam - just my opinion)
0.5% Optiphen + (just in case - it's going to be sitting in the shower)
50% fine sea salt (scrubby)
So, you will notice the glaring error - no beeswax, therefore a 200g bar disappeared in one shower.
It was OK, but miles of room for improvement.