Originally posted by kypfer The lens-cap solution is far more flexible … you can adjust the spacing to fit in the lenses you particularly own, so, potentially, getting more in, rather than having to leave large areas of empty space around each mount "just in case"
You could get the file for the rack and modify it to the dimensions of your lenses. That's something that could even be accomplished with a free, online CAD tool like Tinkercad. Probably a 15-minute task.
I'd print this out myself, except that I have a $200 Monoprice 3D printer with a maximum print size of maybe 5" or 6" on a side so it would have to be printed in sections and glued together. If you have a printer big enough to handle it this would cost maybe $1 or $2 in filament and a few cents in electricity.
I've printed a number of photography-related things, including double-ended rear lens caps, holders for two D-LI90 batteries (color coded, one red for the spent batteries), hotshoe covers, aperture plates for my Lomography Daguerreotype lens, telescope-to-K-mount adapter. It's very handy.