Thanks for asking! Although I have samples of the dice manufactured, the cost of a full production run is large due to minimum quantity order constraints. In particular, there are additional manufacturing costs for each additional color of dice, and so these are unlocked via stretch goals. The initial funding goal of £3,000 simply wouldn't cover the manufacturing costs for the dice in all colors; let alone postage, processing etc.
This is in part due to the fact that I've chosen to work with a very experienced dice manufacturer with the highest quality dice that they offer. Specialist techniques are used to create the different blends of resins in each dice.