Black acrylic
 

Hi RobbAdams,
Brother you need such small chunk so don’t worry, it’s yours for free. Small pieces witch I can offer are: 10 ½ X24 ¼ ,14X24 ¼ ,10 3/4X49 you can choose whichever you like.
Call me 605-7857 any time

Your other option is to get the acrylic shop to cut everything to spec for you. I did that at industrial for my nano refugium and it worked great. I assembled things myself but I'm sure they could do that too if you wanted.

I chose to have them cut to spec because it was cheaper than buying the tool and bits needed to cut things myself.

good luck and look forward to seeing the finished project