Well,
you could buy an umbo premade and bolt it to a piece of 1/2 inch plywood you cut out yourself. You could go the wok route and bolt in a handle in the style of an IKEA buckler
http://www.truefork.org/DragonPreservationSociety/Ikea_buckler.php (a design I don't really like). You could take a round 16 gage steel disk and dish out your umbo and roll the edges then attach a handle. You could go crazy and try to repouse work one of the face type bucklers from Paulus Kal. You could try and make one of the octagonal type bucklers from Talhoffer, or you could try to make one of the pointy cone type bucklers from the I.33. Or you could make one of the wavy type targes you see used with buckler techniques in cut and thrust manuals
The point is there are many types of bucklers out there and different types will be better suited for different forms. I recently completed a 16 gage cone shaped buckler with the grip set recessed in the buckler and discovered that mass distribution can be as important in a buckler as it can with a sword. The way the mass moves can add to or take away for the style of use you are going for. The type of buckler shown in the I.33 allows for easier handling of the buckler in order to protect the sword hand.
Making your own umbo is a good beginners armour type project. Just sink it into a dishing form such as a bowl cut into the end of a log with a rounded off hammer face (a ball pein hammer works, but will give you a rougher starting surface). After you have the depth you want, then you have to planish your umbo over a ball stake in order to get the surface smooth for polishing. The tricky part about an umbo is getting the flange even. I recommend drawing a circle on your steel showing the width of the flange you are trying for and dishing from the inside edge of the circle and spiral your dish into the center.
As for your grip, remember that you do not want a perfectly round grip, you want an oval or square with rounded edges for your grip. This allows you greater control over the face of your buckler, which way it points, and how easy your buckler will be to table with a really hard strike. I like to make my grips from 1 inch strap about an 1/8 to 1/4 of an inch thick. I cut it to length, drill two rivet holes in each end. Put any bends in it I need with a vice and a hammer (you can do this over the edge of an anvil like object as well), then I attach two 1/4 slabs of wood to both sides of the steel strap with epoxy reson, allow that to cure, then I use a drill press to drill 3 holes through the middle of the grip and finish securing the wood to the steel the same way you put slab handles on a knife with a rivet of some type. It can be as simple as piening some brass rods into rivits. With a wooden faced buckler that has a bolted on umbo, you could just use a piece of hardwood, such as poplar for your grip and shape the grip how you like. My last buckler I also leather wrapped the slab type grip and it is a really nice grip that has characteristics of a Albion sword grip.
If you are just looking to purchase a buckler, there are several makers out there who can sell you one. For instance, I make and sell a 1/4 inch plastic buckler that is good for use with wasters, padded weapons, and steel blunts. Other makers make bucklers for various uses, from essentially wall decoration to surviving the pounding of an SCA match. For our purposes, I reccomend a 16 gage buckler with rolled edges and a deep center boss that your hand fits in without hitting the sides or the inside front with your knuckles. 13 and 14 gage bucklers tend to start being a little heavy for our use in my personal opinion.
hope this helps.
Brian Hunt
GFS
