Thirty, or 30, is a Numberblock made of 30 blocks.
Prototype Designs
Arifmetix's design of Thirty is white with yellow borders (10x3), 3 decagram eyes in the colours of the first 3 Numberblocks (3x10), and gloves with 3 stars on each ((3x5)x2=15x2=30)
PBS66Wikia's design has three ten-blocks with yellow borders, six red star eyes, a jester's hat, six hands and gloves, and is arranged 5x6.
Jamil's Thirty doesn't have much details but he has a array display, which means he is a super rectangle.