I was commissioned by a DIT to design a better Preston F/I mounting bracket. My solution mounts solidly to a cart, and retains the F/I using a spring-loaded clamping arm. This makes it very easy to remove the F/I if needed for run and gun, but equally easy to secure it in place for transit or stage days. No need to remove screws from the F/I, great for shorter jobs and rental units.
I print them in PETG with a silly number of outer layers for strength, and then heat-set all the 1/4-20 mounting threads.
See more over at https://www.first.ac/product/preston-f-i-unit-mounting-bracket