First, a very trivial change which helped a lot. The Folger kit includes a small plastic loop that attaches to the top of the left hand Z motor to guide the filament. They say attach it to the front outer corner of the motors. Moving it to the back inner corner gives a much straighter path for the filament, and the spool moves more easily as a result. I also printed a small cylinder to act as a spacer between the spool and the frame. If you don't do this, the left hand end of the X carriage rubs against the spool. I haven't seen any evidence of this affecting the prints, but it seems like a bad thing.
I made a mount for the LCD controller which clips to the top of the frame. Here's how it looks:
The model files and another picture are here.
On the extruder, I added a fan shroud which should direct some air to cool the object being printed, using this model. I'm not sure how much difference it makes. I also attached a light as the extruder casts a shadow making it hard to see the details of what is happening. Thingiverse link here, and here is how one version of it looks:
The Thingiverse link describes the electronics. In short, it is three clear LEDs and a 220 ohm resistor, wired to the 12V output of the power supply.
I protected the electronics in a couple of ways. I considered printing a box to put round the electronics. None of the designs I found were quite right, and some didn't print properly, so in the end I made some brackets which can be clipped together into a kind of cage:
Here's the model for this one.
Lastly, I added a cover for the power supply and a power switch:
The cover comes from here, and the power switch box from here. I don't much like this switch cover. It has a single hole for a screw so it's not very solid. I chose it mainly because I had a pack of rocker switches the right size to fit it.
That's all for now. My next project will probably be a rebuild of the Y bed.