A fabric (see photos),
A saw (for cutting),
A hot glue gun, and
*OPTIONAL* Some sand paper (for sanding down the rough edges of the PVC)
Step 1: Getting the Piece
First, find or buy a PVC pipe that you can fit your arm through, then cut it to the length that would cover most of your lower arm.
Step 2: Cutting It Into Shape
Next, cut down the PVC vertically (see pictures) then when it's cut all the way into two half pieces (see photos again) then you're all set for the next step!
Step 3: Details
Now hot glue a glove in like so (see pictures) (also, old gardening gloves work best) then after that, find a way of keeping the back on like so (see pictures again) and to attach it just use duct tape and some velcrow.
Step 4: Decoration
After you are done, you can spray paint or deck the gauntlet our with duct tape (as I did, see the pictures) or just leave it blank!