Here is a partially complete gantry. The most striking thing is how light it feels. I calculated it should weight about 3/4 pound less due to no steel rails, but it feels like it weighs half of what it used to even with the motor installed. This should give better Y speed and accel. The original plan was to use the same old single bearing v wheels. I decided to use the double bearing ones on the Y. The carriage will stay the same.
Originally I said the people at the $64 backer level would get a full upgrade kit. Adding 9 wheels and 9 more bearings was not in that estimate. If you want to change your wheel and you are at the $64 level you will have to pay for them.
I test fit the gantry in the frame and it fit perfectly (I love CAD!). Installing the bottom wheel was not an issue (and only required two hands). You put the eccentric spacer in. Place the V wheel on the v rail and against the spacer and push the screw in from the other side.
This shows the notch in the idler bracket. I did not want the notch to compromise strength so I cut less off the face. This requires a different length of screw (16mm) which I do not have yet, so I added spacers.