If you fight round shield in SCA Armored Combat you will probably need to make one at some point. Yes they can be bought but that is one of the more expensive ways to go about having one. You can actually make one fairly inexpensively and it will suffice for your fighting and training.
Start with a 3/4″ or 1/2″ piece of plywood. You don’t have to measure it to be perfect but it can help with balance and set up if it is. Make sure you don’t have any bad spots such as knots in the wood. These can weaken the shield. If you can not find a piece of wood without one, try to get the knot near the edge where you will not need it to be as strong. Cut a good size circle that you will be able to weild and will protect you. Of course if you have been fighting round shield prior to this, you will know about what you can use comfortably.
Once you cut out the shield you will need to find the center of it and cut a hole big enough for your shield boss to fit. This you should measure so you do not waste the wood. Measure twice and cut once. You can use either metal or plastic for your shield boss. These can be purchased at fighting events, online, or even at thrift stores if you use old dog bowls for the shield boss. And don’t laugh about the dog bowls, two of them together makes a solid center shield boss for protection.
You can also buy a handle in the same places you get the center boss. If you don’t want to do that or can’t wait, you can make one form a thin piece of flat steel. Cut it down so you can hold it easily, but cover it so a bare hand will be protected. You will have to connect the handle and center boss to the wood. Screws that fit just through everything with nuts are good. You can also get a special kind of wood nut called a T nut that will bit into the wood and is flat on one side. The actual screw will be hidden in this “wood” nut and then you have nothing to worry about sticking out. You will need longer ones to go through the handle and center boss than just around the center boss.
Lastly you have to cover the outer edge of the wood shield. The best thing I’ve found is water hose. The kind that is black and holes all through it to water a whole area at once. It is fairly inexpensive and each to work with. Measure your outer shield and cut your hose about 2″ longer. This way if you miss calculated, you should still have enough. If you calculated right you can overlap it. Drill small holes all the way around the shield and use zip ties to attach the hose to the wood. Make sure you cut the zip ties long ways so there are not sharp edges. Then test out your shield.
This is where I purchased my center boss and shield handle. They sell at Pennsic War or you can go in with other people who need to purchase the same items to cut down on shipping charges.