I liked the original design but found three issues. First the holder is too shallow for bigger soaps. Second the filler just sits freely and is easily flipped when I pick up the soap. Third the flat bottom is too slippery on flat wet surfaces. I revised the design to address all issues by
cutting lower the filler holders
creating a locking mechanism that locks the filler in place (can still be removed)
- making non-skip tread on the bottom
The soap holder is now close to perfection. Enjoy!