After realizing I only use 3 of my keys on a daily basis, I decided to make another, slimmer, key holder. I thought it would a good idea to document the process in photos for anybody who is feeling the diy urge to make their own.
Step 1: Materials needed Donor tool (in this case, a $5 Winchester multi tool from Walmart)
Copies of your keys (you should be able to fit 4 keys using this tool)
T8 torx driver (to disassemble this particular tool)
Dremel w/ cut-off wheel and sanding drum
Bench vise
Drill
*Loctite
*File
*Brewskis
*optional
This little guy actually has a nice assortment of tools, although it does feel a bit cheap compared to a Leatherman. But that doesn't matter, because we'll be taking it apart now.
Step 2: Disassembly 
Using the t8 torx bit, you should have no problem disassembling the multi tool. Be sure not to lose the bolts and washers, as you will be using these later. This tool is much easier to disassemble than the Leatherman Micra that I used for my first variation of a keyholder.
Step 3: Cutting the keys 
Time to cut the keys. You'll want to clamp the key down in your bench vise and have your dremel ready with the cut-off wheel. Don't go too crazy and chop the whole top right off. I generally cut it straight off at the keyring hole and down the sides. Leave enough length for now, you just want to get a rough shape of how it'll be.
Now you want to clean up your cuts with the sanding wheel and a file. You want the keys to sit flat in the tool, so take your time with this.
Ultimately, this is what you want the keys to look like (ignore the hole in the bottom key... that was the key that was covered in plastic in the previous picture). I used one of the tools that I removed from the multitool as a template to round the ends and grind the notches. So basically, place the tool over the key and mark where you will be drilling the hole. Clamp the key and the tool together in the vise and use the sanding drum to round the edges to match. The file will also help to make the notches. Getting this right will ensure the keys lock into place the same way that the tools originally did.
Finally, mark the holes again and drill.
Step 4: Mock up 
The tool was longer than it needed to be, so I decided to chop off the tapered end since it was of no use to me. I rounded it off with the dremel and filed it smooth.
Upon test fit, I realized the notches should be deeper to make it easier to access the keys. I grinded the notches down a bit and smoothed it out.
Step 5: Re-assembly 
On mine, I have 3 keys and the bottle opener from the original tool. Between each key you'll probably want to put a washer so that the keys open smoothly and don't rub on one another. It's a bit tricky to get the washers in there, but keep trying, you'll eventually get it.
If you have it laying around, you may want to put a dab of blue loctite on the screws threads so that they don't loosen up on you down the road. I didn't have any, so I used a little clear nail polish, heh.
Hope this helps anybody who is considering making their own.