Several years ago I had the notion to take an old bicycle multitool and replace some of the tools with my house keys. Due to laziness and a lack of mechanical know-how, I never did it. Recently I saw the work of someone who had a similar notion. The journeyman replaced the blades of the Leatherman Micra with his house keys. Having a spare Leatherman around I decided to replicate his work.
Using two sets of pliers, the screws which the tools pivot around were removed. Each screw was gripped and twisted until they came loose. It took a decent amount of torque as the screws are superglued together as well.
After removing the screws and carefully retaining the tool blades, washers, and backsprings which came out, a tool was used as a template to determine how much of the key handle would have to be removed.
Initially I used a Dremel rotary tool to remove the material, but a hacksaw proved to be much faster. An 11/64 hole was also drilled into the key.
The hacksawed areas were filed and then the tool was reassembled with the keys in place of some of the tool blades. Initially, I had a key on each side, but this only allowed for one tool on each side. The keys were just a little bit thicker than the tools; enough to prevent two tools and a key from residing on one handle. Ultimately, there is a tool handle and a key handle.
There is no blade on the tool because I typically carry a separate pocket knife and because the retained tools are generally allowed in areas where knives may be prohibited e.g. government buildings, airports, etc.
The process was straight forward and now I have a small complement of tools with my keys. If any one else attempts to replicate this let me know how it goes. The best piece of advice I can offer is to retain the order of the tools and backsprings. The constraints are rather narrow facilitating need to reorder things carefully.
There is possibility of bending the already hacksawed and damaged key, but if I ever broke it I would not be too concerned. There are keys everywhere, they are just in the shape of rocks.