fc: condenser focal lengthalphaQ: condenser prism wedge anglefob: objective focal lengthalpha: objective prism wedge angleOne aspect that I haven't seen discussed much in relation to DIY DIC is the condenser focal lenght. It seems to me that slightly mismatched prism combinations could be tweaked to work better by altering the focal length of the condenser. Of course, this is what we do when we change top lenses on the condenser. But this only gives you a limited number of combinations. One thing I am going to experiment with next is to introduce various diopter lenses before the condenser to alter its focal length. I'll report the results in due time.I'm very intrigued by your idea to make your own prisms. I very much look forward to hearing how it goes and learn from it along the way.