Andrew O'Neill
Moderator
Don't do it. Make a pin hole in a lens board.
I've already done that, in fact, I have several. I've always used my LF camera... I miss my TravelWide 45, which could take a 90mm lens or pinhole. Sadly the focusing helicoid imploded rendering body no longer light tight (was a serious design flaw which you probably heard all about). The Cosmos is similar to the TravelWide, minus helicoid.