Great idea - just a little too steep of a taper, but would be a quick start.
Here's an example of what can be done with patience and some skill: a LEC handguard made from a piece of walnut with just hand tools and a drill press with a round nose cutter (and obviously an improvised fence on the drill press, perhaps a mortising attachment fence?) Made by Tony B. whom some of us know. A gent and a craftsman in the best senses.