From the update:
Due to your great support we have unlocked a new, purchasable Curved Corner Add-On Pack. This set consists of 16 Curved Corners and 8 Curved Half Floors. It will be available in both Dark Gray and Expertly Hand Painted versions. You can pledge for either 1 set, or a more economical 2 set offer. The price of this set matches the Diagonal Wall Pack. Please remember that this Add-on is a specially priced* Stretch Goal, so we can only offer it to backers pledged at the 2-set level and above.