Hello, Diego.
A few months ago I started making homemade decals.
I turned a civilian 1/76 Cararama-Hongwell car into a police car. In addition to the new paint, I wanted to add some decals made by myself to make it as close as possible to the real model.
My knowledge of decals was nil, so I started from scratch. Looking for information on the internet, I found a couple of pages that explained the manufacturing process, as well as an online store where I could buy the virgin decals needed to print them myself.
After a lot of patience and effort, I finally managed to produce some pretty good decals and get an interesting car. As soon as I have time to take photos, I will post them here on the forum, in the 20mm-1/72 scale Gallery section.
I post the links to the three pages. They are all in Spanish, but if you speak Portuguese you will not have great problems understanding them. If not, the Google translator works miracles, hahaha.
I hope I could help you. Greetings.
Santi.
https://www.laguerradelanillo.com/miniaturas/taller-de-modelismo/1371-fabricacion-y-aplicacion-de-calcas-caserashttp://www.modelismoaviones.com/blog/fabricar-calcas-caseras/https://www.carminahobbys.com/es/53-calca-virgen