Cost and Appearance of Different 3D Print Resolutions

I had done a post some time ago comparing resolutions but thought that I would do another one using a model from a customer order.

600 micron nozzle with 300 micron layer height.  Time to print (each): 00:49.  Cost (for ten): 31.74
400 micron nozzle with 200 micron layer height.  Time to print (each): 01:10.  Cost (for ten): 41.17
400 micron nozzle with 150 micron layer height.  Time to print (each): 01:32.  Cost (for ten): 49.86
400 micron nozzle with 100 micron layer height.  Time to print (each): 03:07.  Cost (for ten): 62.90

Looking at the costs by time it would appear that my costing for the 100 micron layer print might need some adjustment (up)!

Time (Minutes)	Cost	Cost per Minute
49	£31.74	0.6
70	£41.17	0.6
92	£49.86	0.5
187	£62.90	0.3