A huge backyard can be a great space to add a lot of outdoor play equipment for kids. Here are a lot of awesome DIY ideas that you can consider when you want to start on a project specifically for kids.
1. Build a custom playhouse for your kids.

photo by thehandmadehome.net
2. An old trampoline can be repurposed to make a kids playhouse.

photo by pinterest.com
3. Set up a tetherball in your backyard.

photo by stylewithcents.blogspot.com
4. Make a kid’s science station by recycling a cable spool.

photo by tpcraft.blogspot.com
5. Build custom seating for a sandbox.

photo by lifestyle.yahoo.com
6. Set up an outdoor movie theater area for your kids.

photo by hellopapermoon.com
7. Build a kid’s sized arbor bench to add to a backyard play area.

photo by thecraftingchicks.com
8. Make a vertical tire wall climber.
9. Build a custom sea saw for kids to use as play equipment.

photo by classyclutter.net
10. Install an in-ground trampoline in your backyard.

photo by allthingsthrifty.com
11. Build a mound slide for kids to use in your backyard.

photo by mummymusingsandmayhem.com
12. Set up an outdoor play kitchen with real pots and pans.

photo by woohome.com
13. Make a custom sandbox by repurposing an old bookcase. (REPLACEMENT)
14. Make a water blob that is leak-proof.

photo by homemadetoast.com
15. Build a custom tire totter.

photo by myfixituplife.com
16. How about a kid-sized balance beam?

photo by thechirpingmoms.com
17. Make a DIY climbing wall for kids.

photo by houzz.com
18. Set up a bag toss play area.

photo by thisoldhouse.com
19. Make a homemade water slide.

photo by happyhooligans.ca
20. Make a zip line ride for kids.

photo by makezine.com