Here is an Octagon Picnic table I designed. If you would like all the dimension and materials needed to make one too here's a link.
https://www.etsy.com/LastLeafStudioSh...
Amazon Links :
Predrill + Countersink bit https://amzn.to/3tLVE4v
Circular Saw https://amzn.to/3toyVv7
Deck Screws https://amzn.to/3NzZeGF
Miter Saw https://amzn.to/3tqqf7f