In this step of my Tin Can Tree project, I'm using Sandy Gel to add texture to the trees. You can do similar things by mixing sand into heavy gel or glue, but you'll get more consistency and shaping out of using sandy gel specifically.
The gel goes on looking white and by using sculpting tools or dentist picks, you can shape it. When it dries, it'll be clear-ish, though you're not going to be able to see through the sandy stuff.
In the photo below, you can see how I've been somewhat random about how I've layered the gel. In other areas, I've teased it out like broken branches and knots. Overall, it creates a thick bark appearance. For the smaller stump, I was more consistent about the bark pattern.
Either way, don't smooth it out.
To get a sense of what the overall effect of the gel is, I've included a couple photos of the trees when painted. First, the general look after priming and second a close up of the bark painted.
I'll get into how I've painted the tree in the next post.
Here's an example of how I used the sandy gel in my earthy wall:
