This device is an orthosis I designed recently for a problem I developed in my hand.  I was diagnosed with a calcification in the volar plate.  This caused pain in the middle finger knuckle especially when gripping or making a fist.  I made this to be a reminder not to make a tight fist to prevent agitating the knuckle.  I hope it can help others.  It should be printed out of something flexible and rubbery like Ninjaflex.  The sizing may vary from person to person.  Once printed snaps are added as an attachment.  Edges can be smoothed with a Dremel sanding arbor for comfort to customize the fit further.  A heat gun can be used to modify the shape after the fact if needed.