Generator Interlock - Square "D" QO Load Center

This is an interlock I designed after seeing a similar layout for a GE load center but couldn't find one for my particular load center. This design will not allow the generator to be on at the same time as the main circuit breaker thus preventing back feeding the main lines to the power company and endangering lineman.

Note - this is for panels with a 4" gap between main breaker and the other cluster of breakers. I did eventually find one pre-made selling for $70+ on Amazon. It indicates it can work on 3 1/4" to 4" gaps. If yours is 3 1/4" you put the breaker on the left side of the box which moves the switch lower allowing the 4" design gap to work. If you mirror my design I believe this would work for you too (not confirmed)

I printed the pictured version in PLA but plan to reprint in PETG for longevity.

I used the following hardware so it can slide back and forth.
Spacer: #6 ID X 1/4 in. OD X 1/4 in. L, Aluminum
https://www.amazon.com/dp/B07DS92CBH/ref=cm_sw_em_r_mt_