I´ve been having a little bit of a struggle with this project, I basically have to make 3 tables that can be attached to each other, so I found a shape that I liked and made it in solidworks. The problem is I cant separate them now, I want the grey part in the picture below to be separated of the other 2 (like show in the sketch below) but I´ve tried all the commands and they either dont let me do that, or the cut is very irregular. Wich commands should i use for this problem? Should I make the 3 tables in diferentes parts? But if i do that how would I be 100% that they would attach perfectly? That the angles would fit perfectly?

Also I want those 3 parts to be hollow on the inside, so I can make separate legs for each other, Wich commands should I use for this? I´ve tried using a sketch and cut extrude throught it, but it ate away the above part and I just want the lower part. I´ve seen tutorials of the cavity command but that also didn´t work.

Any help is welcome, Thank you very much