One of the most challenging construction elements of the tiny house is the grey water drain plumbing.  In a normal house you can run these lines (with a constant downward slope) between floor joists. Not so when your floor joists are made of steel,  run the wrong direction and have all voids filled with foam core insulation. Many tiny home builders simply run their pipes down through the trailer and make all the connections below.  That is not an option for us as we are designing for the Northeast’s cold winters.  Our challenge involves the shower which by its nature has a very low drain point and therefore is very difficult to route to a lower exit drain while staying above the subfloor.  To make a long story short we had to employ an oddly angled pipe straight from the shower drain trap to the exit stack.  This angle created a baseline for the rest of the plumbing which is 12 degrees off axis to our walls and there is no such thing as a 12 degree pipe fitting. To get back on axis, I decided to make my own 12 degree fitting by cutting out a section of a 22.5 degree fitting and solvent welding the pieces back together. I hot melt glued the fitting into a cutting fixture which held it in perfect alignment as I made the necessary cuts. The new fitting worked perfectly and I was rather pleased with myself for the idea and its execution.

UPDATE: I eventually decided to replace this fitting for fears that the solvent weld would not stand up to the stresses of road travel.  The consequences of a failure and the difficulty of repair led me to a more complicated but bullet proof solution. After cutting the fitting out, I tested to see how strong the joint was.  I was able to make it fail but only under very high torsional stress.  The joint would have lasted a lifetime in the trailer but I had no way of knowing this without testing it to the failure point.