"Eco Clean" wrote

| We can laminate over the painting with your idea of those 12"x18"
| laminating self-adhesive sheets.
|

I was thinking of the laminate sheets for going
over glued paper, not paint. In other words:

1) cut out letters and use that template to
spray signs. Done.

2) Glue printed text directly to sign backing,
stick on laminate sheets to protect. Done.

3) Maybe this actually makes more sense, if
you don't use stick-on letters:
Draw letters onto sign backing and find someone
with a steady hand to fille them in with a small brush.

Lots of options. But you'll have to pick
one eventually.