I revised the John 3:16 RBS rev c to include extra bracing so that it did not need support when 3d printed. I also removed one brace that was a problem with that rev. The marbles and the track will probably need to be lightly sanded so that the marbles do not bounce off the track. I found it useful to roll the marble between the finge to find bumps that need to be sanded. Running your finger over the track will help find bumps that need to be sanded. The marbles still bounce down the track and like to fly off sometimes.
The older model can be found here: It took me about 5 hou to print. Raft was used but no supports were used when I printed it. NEW AND IMPROVED!: I've made a shallower veion and it seems to work better. The marbles on the shallower veion are slightly smaller so that they ride lower within the track. This all works to keep the marbles on the track better.