I wasn't happy with the selection of underbelly options available. Each had things that annoyed me... they were too thin, the sunken screw holes weren't rigid enough, or the branding annoyed me.
I'm not sure who the original designer is for this piece. I noticed that every variant available is basically a remix of the others. Whoever the original designer is, thank you for your work!
20% (100% if you're okay with the weight)
I did my final print with 10 solid layers top and bottom with 20% infill