Looking for someone who has worked with custom impressions for hearing aides, What types of quality control processes are used in these types of processes?

Example: you take a ear impression for a hearing aide and then make a ear plug what processes can be used to compare the ear plug against the impression other than having a person do a fit check?

Thanks,

Al

I have hearing aids and therefore impressions first. Starting with mixing the solution, adequate fill and cure rate. One problem we ran into was feedback from my right hearing aid due to insufficient length into the ear canal. Had to get a new impression and send back the hearing aid to be reworked.
So I would say OD, angle, and length for sure.