It is about creating a form with the blend tool and use the new form as a font i put on a letter i painted with the brush tool. The problem is that i can only change the font in that way letter by letter means i have to select one letter and the form, combine it and go on with the next letter, meaning if i want to edit a 100 letter text have to do the process 100 times... Is there a way to select the form and all of the letters at once and change it?
There may be ways to optimize the process for some combinations of letters/ words, but ultimately there are limitations due to how the blend tool works to begin with. You have to come to terms with the fact that creating art can be extremely laborious and tedious, even more so when it comes to creating complex 3D illusions. Other than that of course you can experiment with alternate techniques like gradient-based custom strokes and art brushes.