I designed this soap dish specifically for small square soaps. It is about 7cm by 7cm but I have included the original Solidworks file so you could edit it to better suit your needs. It has a drain port at the front and so is optimal for placing between the taps to drain into the basin. The sloped top surface should allow the the water to drain while the ribs keep the soap raised above.
When printing, make sure you have enough top layers to stop the water soaking though into the inside of the print. I would also opt for a smaller layer height if possibel to keep the rounded edges smooth so they don't scrape away at the soap.
Happy printing!
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