Storage box for 4 x 6 filters

Last year I found the perfect storage box for 4 x 4 filters at the MIT Flea Market (old DEC TK50 computer tape boxes - see previous post). At last weekend's MIT Flea Market I found a similar rigid plastic box which perfectly fits 4 x 6 filters. Look around for 1/4" tape cartridges for computer backup. The cases for these tapes have an inside dimension slightly bigger than 4 x 6. Each case will fit 6 resin filters. I'm going to make protective dividers by cutting up some mylar (or a similar material). The cost: ~ $1.50 / box (tape included). Much more compact (and less expensive) than the Lee filter wallet.