STL files for my 3D printer

I need the following created in CAD - 26 .STL files in total.

A mould for each letter of the alphabet in 'Waltograph' (uppercase) font which I can provide. Each letter will be the an empty hollow with a 2.5mm wall thickness all round. The depth of the cavity will be 15mm; total depth of part therefore 17.5mm. Font size not determined but should be approx 100 x 50mm. Each letter will have a lip that creates a 5mm border; again with 2.5mm thickness.

You will need to do the following;

1. Define an appropriate font size, given 100 x 50mm area guide.
2. Create an extrusion 17mm deep with the letter cutting 15mm into the part centrally.
3. Repeat for each letter of the alphabet.
4. Send the file after 'A' is completed and I will check it in my print software before approving the rest of the work to go ahead.

N.B. I am a mechanical designer so know exactly how long this will take. I am separated from my laptop with sufficient hardware for the CAD software due to the pandemic.