I used and existing toddler bed frame and repurposed it as a trundle bed so we could add a 3rd bed into our kids small bedroom. You can easily make the bed frame too.
Check out my blog post with steps on how to turn a toddler bed into a trundle. Great space saver and it's much easier to pull out from under the bed on the carpet (and easier than a full size trundle).
Estimated Cost
$0-30
Estimated Time Investment
An Hour or Two (0-2 Hours)
Recommended Skill Level
Beginner