might be some repetition but here's another couple. A kitchen palette knife, stainless steel for preference. Rolled up bamboo beach mat.

A friend of mine also has a home made flogger made from 3 lengths of bungee cord about 2.5 ft long. Remove the outer coating from all but the last 4-5 inches to expose the individual rubber strands within. Bind those last few inches together to make a handle. Works best if the rubber is well coated with talc