How do I build an ottoman?

See if this gets you started!

https://www.diynetwork.com/how-to/make-and-decorate/decorating/building-a-padded-ottoman

https://www.homedepot.com/c/ah/how-to-build-a-storage-ottoman/9ba683603be9fa5395fab9000d4e8ac

https://www.anikasdiylife.com/diy-upholstered-storage-ottoman/

Depending on the size of ottoman you want, and how high, here is on idea:

https://pin.it/cje34ozwrgzlhf

I would check on line to a site such as Houzz.com to see if there are any plans.

Depends on what type of ottoman you want. I took a short milking stool and put foam on top and then covered with material that I stapled on the underside. I then put decorative furniture tacks around the edge to fancy it up. Looked cute and worked well for the kids. I also took an old wire milk case, painted it the lined the inside with different colored painted cardboard so you couldn't see what was inside. For a lid I used a piece of 1/2" plywood cut to just hang over the sides of the basket. Covered it with foam and material and then put another smaller piece of plywood on the bottom side that would fit inside the basket. Kept the lid from coming off and moving around. The kids loved keeping their little items in it like they were secrets. I did end up putting cardboard or another board on the bottom of the crate to keep it from scratching the floor when they dragged it around but that wasn't hard. Just glued a heavy piece of cardboard to the bottom. When that wore off I glued another on. Kids used it all the time.

You can make an easy ottoman by repurposing a coffee table. Here's a tutorial that might be helpful.

https://www.theshabbycreekcottage.com/diy-ottoman-from-coffee-table.html

Here are several neat ideas! https://www.hometalk.com/search/posts?filter=diy%20ottoman