Measurment of tool nose radius

How can the tool nose radius be measured when it is not a given? Assuming no shadowgraph or microscope.
Looking for a "poorboy" solution if possible.

Radius gauge? You could even cut though sheet material held in a vice with the tool, measure with a mic. and that becomes your radius gauge for that size tool.

Or am I missing something?

Doddy - Sorry I should have been more explicit. I am wanting to measure the tip radius on carbide turning tools.

Mk 1 eyball with some small drills, like doddy said drill your holes in some plate and put a light behind it, that assumes you have a selection on small drills.

Thanks guys. Excellent advice.