Where to find playground border 10-12 inches high? Or any temp border

Contractor was going to level yard and add plastic border and canceled two weeks in a row and is now walking from the job. Need to get border up by Monday.

I know you can order plastic borders online but won’t come in time.

Any ideas where to get a border 10-12 inches up locally? Don’t mind driving a bit to get it. My only thought is to use 6x6s temporarily and wait for borders to come (but waste of money on timber).

Thank you everyone