One of my favorite and least expensive tools for adding texture to my work is DAP DryDex Spackling. I love gel medium as well, but prefer the chalkiness of spackling and the fact that I can sand or carve into it once it is dry. And DAP is fantastic as it goes on pink and dries white so I know when I can work into it without constantly sticking my fingers into it. Plus, another great bonus, is that it's inexpensive and readily available at any hardware store.
On the negative side, it can crumble off flexible surfaces like canvas and paper so I've begun mixing it with gel media to create more flexibility. I'm also careful about the amount I use on a surface that isn't rigid. Once it dries, I sand down any sharp ridges, give the piece another coat of gesso, sometimes white and other times black, depending what I'm planning to do on the top.
Lately I've been giving a lot of thought to Art vs Craft as what I do can often fall into both categories. I really dislike the separation because I grew up learning crafts - weaving, beading, embroidery, sewing, crocheting, knitting, wood & leather burning - which taught me composition, colour, design and how to commit to a project until it is complete. When I finally had the opportunity to take an art class when I moved to Alberta during grade 11 my teacher mentioned that she wasn't surprised that I had the same understanding of the elements of design as her other students who had studied art throughout their school years.
I think any form of creative expression is necessary...cooking, sewing, music, gardening, photography....I believe we all need to dream of things in our minds, to create something with our own two hands. And I whole-heartedly believe that every single form of that expression is art.