I brought this as a prop to take some photos of in wedding shoot, and I have been so impressed with how it's lasting! It's honestly been in my garden all summer (and let's face it, it's rained, a lot!) yet the pen hasn't budged! This is just a bronze sharpie on the glass, and it has done very well for itself.
I recommend if trying something like this to pop a template underneath I did mine with pencil and paper (it's not often I use a template but it's not often I work with circles so wanted to make sure I got spacing right)
If you need help with handwriting don't forget to pick up books, worksheets etc here
Any questions, let me know :)
Wedding Ideas Magazine - Spotlight on The Chalk Spot