Pat Mitzel, one of my best local riding buddies and a member of the Ryan Leech Connection where I’m a part-time coach, has published a 27-page PDF titled, The Backyard MTB Feature Build Guide. It’s available via this post, A DIY Guide to Building Backyard MTB Practice Obstacles on the RLC blog. The 27-page guide includes a tool list, materials, and details for how to build each feature.
The post also includes a 2.5-minute video of Pat riding many of the obstacles: