Those old wooden cassette tape holders work well. Sizes vary. You just pluck out enough of the slats to configure your cartridges how you like them. The larger ones can get heavy when full, but with some proper supporting brackets you could hang them on a wall.
Here is a large one eBay Auction -- Item Number: 230619477566 on ebay, but they can be found at flea markets, garage sales and thrift stores, usually for cheap.