I have terrible handwriting and try to avoid showing it as much as possible -- but this sounds like a great personalized project!
There is also the option to print letters on fabric. There are many ways to do this and some printers/processes need some added treatments to be stable. You can also print iron on transfers -- if doing this follow instructions so you don't get reversed letters. With printing you can choose fonts and sizes.
Some of the printer options are easier to find in an office supply store rather than a craft or fabric store, look where they have "fancy" papers.
https://www.avery.com/campaign/fabric-transfers
https://www.avery.com/products/labels/3384
There are a number of brands other than Avery, can find a lot of options on Amazon or from searches for printable fabric sheets.
My b&w laserjet did very good with ironing regular (prewashed, no softener or other wash additives) freezer paper to fabric. You can do searches on the freezer paper technique.