I don't understand the question, unfortunately.
When I designed these, I designed them to drop in between the rails. Then the pieces that are between the tracks drop in as well.
www.therailwire.net/forum/gallery/55/5820-240826131054.png[/img][/url]
I'm thinking of something like an Atlas re-railer section. Those are injection molded around the rails, of course, but what i had in mind was something like a printed part with 'channels' that allow rail to be inserted from either end. Alternately, it could be a multi-part approach where the pieces can sort of snap into place around the flex track (it might be easier to remove the plastic ties from the flextrack where the crossing will go.
getting a single piece printed part that keeps each rail seated and correctly aligned in gauge might take a bit of work. I’d be worried about resin fouling the track insert areas and causing out of gauge problems.
With the tie strips that I have done, I haven't had too many issues with the track gauge, as long as things are properly scaled to the correct dimensions.
Anyways it was just a thought, since I have done parts like these and found it a little tricky to get good placement/alignment of individual parts, esp trying to keep the field-side pieces (sitting on the flextrack 'spikes') snug against the rail heads without slipping up too high.
Ed