It's nice to hear of others having a go.

When we make straps We use an adjustable strap cutter they aren't that expensive the one we use is American.
To finish the edge the simplest way is to soak a cloth in some hot water (Hottest you can hold)holding the strap tightly draw it though the cloth several times. It gives a good polished finish to the edge. We don't use dyes on the edges.
Great results you got too by the look of it