Stackable Box V6

This is a remix of Yuan4114's Stackable Box V4 -> https://www.thingiverse.com/thing:647425 which is a remix of Gushie's http://www.thingiverse.com/thing:447213, which is a remix of 1986breeze's http://www.thingiverse.com/thing:234669, which is a remix of martinhering's http://www.thingiverse.com/thing:177814

I adjusted the design to increase stability when stacking in the back. The result should be another drastic improvement to stackability and no significant increase in material usage or print time. The design is fully backwards compatible with both Gushie and 1986breeze's versions (in that they'll stack).

This version only adds about one gram of filament from V4. You should get about 31 boxes for every kg of filament with this model.

Printed 5 of the V4 version before I realized it looks like the Leaning Tower of Piza, so here is V6(figured there was 50+ remixes so this one is named V6 :P) with level support in the back end too, not just in the front.