Using Traxxas Big Bore shock with Losi mini t springs is a common mod to getting a good shock for crawling.
Losi mini t springs are hard to find lately (at least where I live) but Desert Lizard springs are common but they do not fit as nicely as the Losi ones. These parts should help.
The perch should be printed with the flange on the print bed, supports enabled, as many perimeters as needed to be printed solid inside.
The ring adapter makes sure that the spring is stable. The Desert Lizard inner diameter is not large enough to fit over the narrow part of the shock body like the Losi ones and not small enough to be stable on the end of the shock. The ring makes sure that the spring doesn't slip and stays center. Should be printed with the side that is cut flat on the bed, with a brim and as many perimeters as needed to be solid inside.
The author marked this model as their own original creation.