As part of a workshop I am teaching, I designed this as a teaching aid to demonstrate the YHT rule for support-less 3d printing design. I do not recommend that someone limit their design because of this rule! It can be overcome.The YHT rule states: Y prints, H prints o.k., and T does not Print.To explain, Y prints because angles of 45 degrees or less have sufficient material for a new layer to form without supports. H prints o.k. because it has supports on two sides, and usually just has a small amount of loose filament on the under side. T does not print because there is insufficient material to act as a support for the next layer.This also has a second set of letters to show that this issue can be overcome, sometimes as simply as rotating the object on the build plate. There are other ways of course, but this was one of the easiest to represent in a single print.