I have dried several pieces of wood in the microwave. If they were
turned green and put in the microwave, they all warped. Some a
little, some a lot. Some looked neat, some were correctable back to
round.

To avoid a lot of fancy equipment, get an old (or cheapie) micro to
start with and a postal scale.

A couple of years ago I needed some deep bowls for candy dishes with
stands, but didn't want to use any of my good wood stash. They were
give away gifts, and I didn't get much for them.

I had a large 10" piece of ash that was given to me, and I cut the
diameter to 6 - 8" on all of the blanks, and wrote a control number on
them with a sharpie. I put three in at a time, and hit them for 2
minutes on high. Let them rest, then weighed them. I did this while
I was turning other things, and kept up a log of times and weights.
It worked great!

I knew to quit microwaving when there was no weight loss for two
different sessions. If the wood hissed or sizzled during the rest
time, I let it sit unitl it quit.

At the end of the experiement, I put all the blanks in two 5 gallon
buckets with a lid on it, and left it there for a couple of weeks.
When I pulled them open, they had lost a little more weight/moisture,
but no much. The point of leaving them alone for a couple of weeks
was to let the wood redistribure any remaining moisture.

This method works great, and is effiecient for these larger (6-8" wide
and the same length) pieces. But with something as small as a pen
blank, I would think you could micro one day and be turning in a
couple more.

Robert