As always, more progress! I've installed the previously mentioned pulleys and worked on the exterior frame. Also, a few redesigns of the hotend mount have taken place. Here's a mockup:
Most of the effort has been in building the exterior frame. This frame/shell will keep heat in and fingers out, hopefully reducing part warping. The XY motors and extruder will be in the rear of the printer where the wooden crossbeam is located in the above picture. The crossbeam is actually part of the XY motor mount, and will be lower and behind the steel frame. The blue pulley mounts at the front will hold the 2 remaining pulleys to complete the H-gantry system. A power switch will be added to the bottom front of the printer which will trigger an ATX power supply. Also tucked underneath the print area will be the Raspberry Pi and Printrboard controllers. Additionally, the Z axis motors will be anchored to the bottom panel, with the mid-panel providing additional reinforcement to the vertical smooth rods.
I haven't decided if I should have a clear acrylic top or not. The extra visibility would come in handy if there's problems with the printer, but completing the cabinet-style appearance isn't a bad tradeoff! Spool mounting has also been a persistent problem. Housing the spool within the enclosure would drastically increase the size and weight of the printer. However, mounting it externally would harm the look of the printer and make it more difficult to transport.
Once the basic frame structure is complete I'll be working primarily on the Z axis and auto bed leveling (ABL) probe. My current plan is to transfer the motors from my Printrbot LC onto this beast, but I still need the LC to print components! As a result, I'm holding off on testing for now!