These are slightly-modified versions of gaaZolee's temp towers, this design is all his, I'm just tweaking a couple things: a) the models have been scaled by 150% (which consumes a little more plastic but surface features like ringing, blobbing, or overextrusion are easier to distinguish), and b) I shifted the model down slightly to discard the unnecessary text on the bottom. This change should make the temp tower more effective and easier to print.
Don't forget, you don't have the print the whole thing every time... If the idea temperature block is early in the print, you will likely get significant underextrusion, and possibly even clogging before the print finishes. Keep an eye on this while printing!