I enjoyed using a dual tip pen (Tombow) to write the envelope. Being able to use the same ink with two different kinds of font is great for effortless consistency. It's a lovely pen to use as a beginner. After some more practise I will graduate to the Pentel pocket pen because I already love drawing with it and look forward to writing elegantly enough to create a contrast with some rough textured brush strokes.
I wrote the letter with Pentel Touch pen, which was much easier to create legible rather than decorative type.
I made the stamp with the same paper as the letter and added some decorative watercolour elements with my Sketching Tin (joacreations.com). I have been practising using the waterbrush and watercolour paints from my tin to write with too. I love the dynamic look of type made with a brush but I definitely need to practise with the firmer tipped pens first.