This is the mk 4 version of my replacement Carriage for the Flashforge Creator Pro and similar dual-extruder printers.Update 1: Mk 1 turned out to be VERY problematic to assemble due to the interlocking parts. Tolerances are likely too tight to build like this. I redesigned to use long M3 bolts to assemble the main body, and changed the way the Y-Axis belt is clamped down from a separate piece to an integrated zip tie channel Update 2: Mk 2 printed well but had a few issues. The Y-Axis belt would rub against the bottom, so I thinned out the design creating a channel for the bottom of the Y-Axis belt. the bolt holes where repositioned and countersunk to use 30mm M3 Hex Socket-head bolts (common to find at any good R/C car/plane store like Hobby Town USA). I also fixed an issue with the strip tie channels so they align properly this time. Update 3: Mk 3 printed well, but the multiple pieces turns out to be a bad idea as it can cause slight misalignments in the bearings. I decided to largely start over with a 1 part design. This one should be printed inverted with support on. No bolts are needed for this design, and the Y-Axis belt is secured with 2 strip ties in the center of the carriage instead of on the outside of it. Honeycomb manual infil has been put in the cross-bar sections for strength and to reduce weight. Update 4: The mk 4 had to be thinned down to allow for the wires behind the heater blocks, and the zip-tie Y-belt clam turned out to be difficult to tighten properly. The Mk 5 has had sufficient room built in for the cabling and a replacement Y-axis belt clamp has been replaced with a clamp that requires 2 M3 10mm bolts to secure. The bolts that secure the heat spreader need to be replaced with M3 15mm bolts instead of the 10mm that are stock due to the thicker crossbeam. The Y-Axis belt clamp does take some cleanup from the support material to properly fit, but it goes together quite well. This model has been installed and is printing very well! (see pictures) Print with ABS, 2.0mm layer, 30% infil (experimental still). Mk. 4 does require support to be printed properly (inverted) The original mk 1-4 files are zipped up here for storage in you want to browse the development process. This is still in test phase. Input or comments much appreciated. I'm working on an additional version that will be much lighter and thinner. I intend on making this the basis for a full Bowden Extruder and laser etcher interchangeable print head upgrades once I'm sure this functions well as a replacement carriage.