Valid May 23rd - May 28th, 2018. Cannot be combined with other discounts or coupon codes. Discount only valid for products specified in the offer. Not valid in combination with the volume discount. Coupon cannot be used toward the purchase of gift certificates. Valid on www.spreadshirt.com. Not valid in Spreadshirt's Partner Shops.
A tesseract is in principle obtained by combining two cubes. The scheme is similar to the construction of a cube from two squares: juxtapose two copies of the lower dimensional cube and connect the corresponding vertices.