Step 1: Finding Your Design
The first step is to find a design for the aluminum knuckles you wish to create.
There are many websites online such as Thingiverse which contain many potential designs.
Pictured are three designs I looked in to, find whatever design you desire.
Step 2: 3D Printing Your Design
Next, take measurements of your hand and estimate how big you want your aluminum knuckles to be.
Using a 3D printer, print the design and test its feel and shape.
3D print different sizes until you have your final size and design.
I printed three different sizes before settling on the middle one in the picture.
Step 3: Making Your Mold
Now we are going to use plaster to make your mold that you will use to make the aluminum knuckles.
The first step it to construct a easily disassembled box. You can use light would but I recommend hot gluing together foam board. You want the box to be sealed, as we will be filling it with plaster.
Now, Look down into your assembled box. Take your final 3d print, and ht glue it to the bottom of the box. This way, It will remain in place and the plaster will form around it. Once the hot glue has dried you pour the dry plaster around it into the box, and then add water and mix until it has formed an even consistency.
Now, we wait for the mold to dry.
Step 4: Mold Part 2
Now you should have a solid plaster mold inside your box.
Next you must gently and carefully flip it upside down, disassemble the box, and you should have a solid block of plaster where you can see your 3D print.
Now, gently and slowly remove your 3D print from the plaster, careful not to crack or split it (Note: You may have to lightly scrape off parts of the plaster mold in order for the 3D print to be removed)
Now you should have you plaster mold, next step is pouring to aluminum!
Step 5: Casting Aluminum
The next, and most intense, step in this process is the casting of the aluminum. Using a method of your choice, melt down aluminum until it reaches a liquid state. In our process, we melted down recycled soda cans using a propane torch and stainless steel tools. There is no wrong way to do this step, as long as you end up with liquid aluminum that you can cast in to your mold.
Now, take the liquid aluminum and slowly poor it across and over your mold. Once you have covered your entire mold, stop and wait for it to cool. After allowing to sit for 10-15 minutes, remove the aluminum from your mold and slowly dip it in warm water to accelerate the cooling process.
You should now have a very rough incomplete mold of your design.
Step 6: Finishing the Product
Now we are going to grind down and finish the casting. Using an angle grinder, Slowly and carefully grind down and remove the excess aluminum until you are left with your intended shape. You can use the angle grinder to reshape the mold to an extent, but be careful, once you grind it down, it can not be reversed to the shape it was.
Now you should have your own pair of aluminum knuckles, thank you for using this instructable, use the knuckels safely!