On sale here for a couple of years have been small elec fans that let you plug in two frozen plastic 'bricks' that gradually thaw and suck up heat and air moisture. How long they last depends on the conditions, but in a room (a small one - or get more than one unit) which has the windows shut so that there is no great current of air thru it, you can get an hour or two per charge. You can then swap the bricks for a couple more in your freezer. You run the fans at a low setting - just enough to circulate air.

It's a slow gentle process, but you can get 5 - 10 deg C difference inside from outside - and by sucking some of the moisture out of the air, it makes a big comfort difference in 40 deg C 95%+ Brisbane humidity! Also not as expensive to run as compressor air-conditioning.

It's not the same as a block of ice - that would only increase the humidity - and those 'water evap' gadgets are useless here in high humidity too.

Actually you can hack up one of these easy enough - a couple of old PC (12V would be fine) PC fans and some of those freezer blocks in a case - with a drip try.