Great thing. It would be nice if it had a wind deflector to protect the print from cooling - i used a business card ;)
Nice! The "Bracket Length" is actually a parameter in customizer, and with that you should be able to achieve what you need: generate brackets that are enclosed (check out the photo gallery as well where I have 3 gray brackets one of them enclosed). The trouble is the online Customizer has a bug and ignores random parameters, until Thingiverse folks fix that you can get around it by downloading the script and running it in OpenSCAD locally.
Sadly i think my printer would fail in attempt to print it ;)