Custom LEGO Compatible Text Brick Keychain. This custom keychain allows you to design a LEGO® compatible rectangular brick with text engraved on all four sides and a half ring at one end to attach a key ring. You can of course also use it to make bricks without text. It can make blocks as small as 1x1x1 (plate height) or as large as 48x48x18 (6 normal blocks high).