I seem to be late to join the craze - I've been seeing those glass "marble" or dome magnets all over, thinking to myself..."how lovely - I bet I could make those." And sure enough, they aren't hard to make at all.
These are made with 1" and 3/4" acrylic cabochons and custom images - they all happen to be desert flora from hikes I've taken! Sorry for the blurry shot - the darn things don't photograph well - seems my camera likes to focus on the reflections on the tops of the domes instead of the bottom image...I'm sure it also has to do with the index of refraction of the domes themselves...but I'll keep my mouth shut and not get too nerdy.
If you're interested, I'm more than happy to trade or sell them...Though if you have a specific flower in mind, I'll have to see if I have it available. Given enough time, I might be able to upload all the images I have available.
And if you are interested in making your own, I highly recommend Not Martha's site for details.