Greg, When I started to print my first TrotFox designed car my plan was to drill a couple of matched holes in each side and use pins to stiffen the joint.
When the car was done, I thought I would just try a butt joint, if it didn’t work, worse case I’m out 50 cents of plastic and electricity.
I lightly sanded / squared up the butting surfaces, placed the car on it’s back on a hard smooth surface, and used a PLA solvent ( SciGrip 4 ) to bond the halves together. I placed a weight at each end to lightly hold the parts together and one over the middle to keep the assembly from bowing. I came back in a couple of hours and the bond was solid. The joint is right between two deck boards, so from the top the joint is invisible. On the bottom there were some small gaps in places on the beams which were quickly cured with some Tamiya putty. The three remaining cars were done the same way.
TrotFox’s design worked out very well for me. Once it was glued, a little adjustment on the bolsters and a little sanding on the coupler pockets was all that was needed. Add paint, couplers, trucks, and detail parts and you are ready to go.
Sorry to derail your thread, Dick, but I wanted to answer the question as well as I could.
John R.