This is how I dry flowers in the microwave using microwave-safe plates instead of expensive devices. This will definitely not work on all flowers but, even in my limited garden, there are plenty that do work.
On a microwave-safe plate, stack: doubled paper towel, flowers delicately laid out in a single layer, doubled paper towel, another microwave-safe plate for weight.
Put this stack into the microwave and heat on high for about 40 seconds (this depends on the flower, delicate petals will dry in about 20 seconds, ferns take about 50 seconds). Check to see if the flowers feel dry, but not crisp. If they still feel really damp, put them back in for about 10 seconds. Repeat as necessary.
The paper towels soak up the moisture and the plates get wet so I dry the plates and switch paper towels between each batch. You can just let the paper towels sit out for a few minutes to dry so that you won’t use so many.
It’s best to let the flowers rest on a paper towel for a few hours before using it in your work. They seem to last better.
I’ve tried a lot of flowers that didn’t work at all and lots that have worked very well.
Experiment! I’ve noticed that the really delicate petals (like, say, a California poppy or an anemone) are very delicate and turn brown if you dry them for more than 20 seconds or so.
Pansies work really well, oxalis not at all. Ferns work great as do acacia leaves. Vinca works well but you can only heat for a very few seconds. Bougainvillea and phlox also look great when dried this way.
As an experiment I did this with a bunch of poinsettia leaves. I also did some at the same time in a flower press. They looked exactly the same when all done (except that the pressed leaves took 2 weeks to get there). I call this method the “Poor Man’s Microfleur.” I was watching a video in which they were selling a special device made for this but didn’t want to come off the $40 bucks or whatever. I thought, “Hey, I could do that with my microwave-safe plates!” The first batch came out perfectly so I got lots of confidence and now I dry just about everything..