The 3DSolex heater block makes changing nozzles a matter of seconds. It makes it easy to switch between materials but I am finding it even more useful to be able to choose a nozzle size based on what I am printing. One of the standard 0.4mm nozzles can usually be found on the printers but I love being able to switch to the 0.8mm or 0.6mm nozzles when I want to print a draft at 0.4mm or even higher or maybe a case or box for which a layer height of 0.3mm is just fine (like the one shown below).
I have started to collect nozzles so had to print myself a box for storage. The little plastic squares remind me what nozzle is on what printer.
The top row are reserved for PLA and descend in size from left to right (1.0, 0.8, 0.6, 0.4, 0.25, 0.15mm). The bottom row are the same sizes reserved for ABS but for the lower left which is a steel nozzle for carbon fiber reinforced filament.
My only complaint is that there is not a reseller in the UK. I have an order in flight from the source in Norway but we are having some shipping problems (with stuff having gone astray) and I think that Carl is tired of me! Hopefully we can get this sorted out as I want to complete my nozzle inventory primarily with additional PLA nozzles (0.25, 0.6, 0.8) so I can print the same size on both machines at the same time.
Speaking of 3DSolex. It is not just the heater block and nozzles that I have purchased from them. I also upgraded the newest of my printers with their steel coupler, I2K insulator to help protect the teflon coupler, and their bowden tube. I have no way of measuring the effectiveness of these last products but based on how well the nozzles perform I am willing to go on faith!