it works great (the cup) i cut a hole on 1 side near the bottom, another on the complete oposite, but more to the top, and a circle on the top (technically the bottom of the cup but i placed it in there upside down) and stuck some fake grass inside of it, it tends to float but i just stick gravel on the edges so it stays down, and my Mister seems to love it quite a bit
and it does not bleed, but where it was shap i took a lighter to it and burnt the sharp edges to a melted curvy thing. its really cutw because he swims thru the top sometimes and then he just literally sets his head on the bottom of 1 of the entrances and just sits there looking around lol. with his tail fins hangin out the other side. he likes it but it took him a while to get used to it. good luck.