An extension of the idea of the warning badge, per Blood Cancer UK.
T-shirt to get you noticed and keep you that bit safer. Message front +/-back +/-sides. Example:
teamshirts.co.uk/basket/caa...
EDIT: I talked to the supplier. They will sell INDIVIDUAL shirts printed to order, or multiples on a pick-n-mix basis, i.e. you can choose your style, size, colour, design.
The unit price reduces as the order increases beyond 6 shirts. For example the unit price of the Men's Gildan heavy T-shirt: for 100 is £11.36, for 20 is £16.18, for 6 is £25.11, for 1 is £27.90.
Therefore it would be useful to know WHO'S INTERESTED?