The tender chassis went together quite quickly with all the 3D printed parts. Upon reflection and further measurement, the rear coupler was .01” too high. I shaved the bolsters down, and then everything looked pretty good – apart from the temporary coarse-scale wheels!
The trucks are Kadee HTC caboose trucks, which are a reasonable facsimile. The hardest part of replacing the wheels was to find some with the right axle length in my collection. I must say it makes a big difference in appearance.
The tender chassis with code 110 wheels 
With P87 wheels.
The two end beams are printed, while the side sills were cut from .06x.10 styrene strip. If I design something similar again, I will make pockets in the end beams for the strip so that I don’t have to cut the strip to precise length.
Overall, the chassis sits too high. It lines up nicely with the cab floor, but now that I see it in the flesh, I realize there should be a 4″ high platform on the tender deck to bring it to the height of the cab floor. I’m still considering how and if I will fix this.
Pembroke:87 
“ I must say it makes a big difference in appearance.”
I would be seriously worried if you didn’t think so, René!
Well, obviously it had to be fixed, Simon! It was more work than I’d wanted, though.