These are great. I've made 10 of them so far and they allow a lot of new track designs. They fit well with at least 3 or 4 different brands of track that we have plus the Duplos.
These printed fine on a stock Da Vinci 1.0 printer. There was only very minimal cleanup of the bridging required after the prints where I just had to pull off a few strands on the first bridged layer that didn't stick well. The Da Vinci slicing software ran this first bridging layer lengthwise which seemed less than ideal but it still did very well with it.