I'm a huge fan of snail mail and I have a project only for this: Love it Forward List.
When I want to include a #wordrocks in the envelope, sometimes I use sea glass. Not just because it's lighter than a rock but because I love the colors.
The best marker for this is Posca Ultra Fine.
You can buy Sea Glass at Amazon.
Join Love it Forward List and send a love letter to someone in need. Encourage someone with your love and kindness. You have the power to light up someone's day. ❤️💌 Love is action!
If you know someone who needs a kind word, we'll love to help: firstname.lastname@example.org