This is a remix of the embroidery hoop design from intofocus, I only altered the size of the hoop to be a larger 7.5" circle. The instructions/assembly remain the same:
"Simply print the 3 parts. In order to assemble it you'll need two M4 hex nuts and a M4 bolt of 50mm. Insert the bolt into the the 'adjustment screw' part and add one of the M4 nuts and tighten this. Add a little 'Loctite' to prevent the nut from loosening itself. Insert the other M4 hex nut in the outer ring and secure it in place with a drop superglue and let it dry for a couple of minutes and you're ready to go!!"
I only had a 25 mm long M4 bolt on hand so I scaled the height of the adjustment screw piece to be 60%/15 mm tall. I wouldn't recommend this if you're using it to sew your embroidery, since you have less room to tighten, but since I only needed to use it afterwards for displaying my piece it held up fine.