Half the fun is to do this on the cheap. I happened to have two fans recovered from an instrument I once worked on in an earlier incarnation (which was being scrapped I hasten to add). These were of American manufacture and so required 115 volts, so I wired them in series to match our 230-volt supply. I managed to find a room thermostat with a change-over switch so that I could have the fans come on when the temperature got too hot. (This is unusual in this country where central heating is common but air-conditioning is very rare). Since the option was there I have wired in a change-over switch so that I can use it in either mode; the on-if-cold option may be useful in the winter to help cool the equipment down as the temperature falls.
Here is the assembly on the end wall remote from the door. The fans are fixed to the wall with bolts that pass through the wall and whose heads are protected by the grill covers on the outside. It seemed sensible to mount the thermostat high up, but when this picture was taken it was set at 24°C and you may be able to see that the dial thermometer below reads 90°F (it was bought in America, so the main scale is in Fahrenheit, but this represents 32°C), and yet the thermostat was cutting in and out, so maybe it is being cooled by the fans. The second thermometer, just out of shot at the bottom, is a max-min thermometer bought in the UK about 60 years ago so that is in Fahrenheit too. I take it as more reliable than the dial thermometer, but the two do not differ by more than a degree or two. I shall reset this and leave it all on whilst we are on holiday in the summer and see how things look on return.
Here is the outside view. Not easy to photograph; I was leaning over the fence to take this. You can see the two grills covering the fans. These are fixed to the grills attached to the fans (like those that show in the picture above) and are sealed to the wall with silicone sealant. I painted the wall white, hopefully to reflect some of the heat. I plan to do the same on the south-west wall.