Cyro AcryliteFF Extruded Acrylic. Machines well, looks really good. That's all i use. Extruded is what you want to use for sumps. 1/4" minimum, that's what I recommend. Allows for a little mess up if your seams arent the best. Takes some practice. Plus you can micro-mesh and make the seams crystal clear. Be on the look out for my upcoming thread for my build. I'll take pics of everything as I progress in the build. HTH.

Ram