just a mention for blotz.co.uk, who make various mdf and acrylic bits for gaming.
they do a range of acrylic tokens for frostgrave and latterly GA - when picking up some 'pit' and 'smoke' ones recently I asked if one of the smoke ones might have a different etched design more appropriate for the 'pool' spell.
they produced this without any fuss or extra charge: think it works a treat:
have enquired if it might be possible to do one in thinner acrylic (this is 3mm) but even so it's fine
might customise it further with some darker blue ink swirls etc.
(* and btw, I'm just a customer and have no vested interest in the company)
** I see they're now listed on the site, and the ice blue version looks very good:
http://blotz.co.uk/index.php?main_page=product_info&cPath=24_230&products_id=1535