Part of the beauty of bikes is that they are simple enough for people to maintain at home, and some components can even be home-built. In this project, I'll show you how I made a bottle holder.

This project can be made with hand tools only, so it's accessible to kids and people with limited workshops. It could be a great introductory metalworking project.

Be creative with materials; I used a piece of aluminum from an old window frame and the kind of wire used for bracing high tensile electric fence corners.

Supplies

Materials:

~3 1/2" piece of aluminum channel (Mine was 1/16" thick, 1 3/8" wide, 5/8" deep, but variation from that would certainly work)
~32" heavy wire (preferably galvanized)

Tools:

Hack saw/metal band saw
Vice
File
Drill
Twist bits (one slightly larger than the screws that attach the bottle holder to the frame, and one slightly larger than the wire you have
Measuring tape)
Square
Marker
Scribe (a sharp wood screw will work)
Punch (the same screw will work)
Hammer
Pliers & tape or a rag (to wrap the jaws in to protect the wire's galvanization)

Step 1: Body: Cut

The attachment screws are typically spaced 2 1/2" apart, but it wouldn't hurt to check the bike you plan to attach the bottle holder to so that you know it will fit when you're done. Mark and cut the aluminum channel an inch longer than this dimension; in my case, that's 3 1/2".

File the cut ends carefully, rounding over any sharp corners so the cyclist won't get cut when reaching for the bottle.

Step 2: Body: Drill

Mark and drill (using your wire-sized bit) four holes for the wire to pass through the sides. There's a lot of flexibility with placement, but I centred them vertically and put them 3/8" in from each end so the wire wouldn't interfere with the screws that attach the bottle holder to the frame. Use a punch so that the drill won't drift from the marks.

Mark and drill two holes (using your screw-sized bit) through the bottom section. These should be centred so that the bottle holder is balanced over the bike's frame and spaced apart by the right amount for the bike (typically 2 1/2"). If you have a tiny round file, it's worth filing these holes into oblong slots so that it's easier to fit to different bikes even with some variation in hole distance on the frames.

Step 3: Wire: Setup

The wire that holds the bottle is a fairly complex shape, but it's not too hard to make if you do a bit of planning and make the bends in a sensible order.

In the diagram you can see the lengths of the various sections. My water bottles are roughly 3" diameter. If yours are a different size, you'll want to adjust these dimensions accordingly and cut a different length of wire, but my wire was 32".

The trickiest part of this project is bending the wire consistently so that it ends up symmetric and fits the bottle snugly. Marking the wire at each of the points noted in the diagram helps with this.

Step 4: Wire: Loop

Bend a circular curve into the middle of the wire. If your hands are up to the job, they're much better than pliers for producing a smooth curve. Check the diameter against the bottle and adjust until it matches. In order to maintain a consistent arc right up to the location of the next bends, I found it easier to bend more than a half-circle and then bend the tails back out to straight.

Step 5: Wire: Arms

Many of these bends are easier to do and will have sharper corners if you have a vise, but you can certainly make do with pliers. Assuming your wire is galvanized, you'll want to protect that coating by using wooden vise jaws (or pieces of scrap wood in the vise) or a rag around the pliers.

Clamp the loop in the vise so that the marks are at the edge of the jaw, and bend over both arms. A block of wood and a few taps with the hammer can help square the corners.

Step 6: Wire: Bottom

My vise is mounted to the bench such that the ends of the wire hit the bench top during this step, so I temporarily bend them out to the sides. Clamp the wire at the next pair of marks and bend it over as before. Straighten out the curved ends.

Next we need a double corner that will take the wire perpendicularly out through the wall of the body and then parallel along the outside of it toward the front of the bottle holder. The first bend should be greater than 90°, so finish that bend out of the vise by hand. The second bend should be as close as possible to the first one while still allowing a solid grip with the vise. I found it necessary to square up this corner with pliers.

Bend the two bottom sections toward each other to make a V.

Step 7: Wire: Sides

Stick one end of the wire through a hole in the side of the body from the inside, then rotate it so the end lies along the outside of the body. Then bend the other end around and repeat. This looks alarming since you're deforming all your carefully bent angles from the previous steps, but the wire should have enough memory of where it was bent that it will be easy to get it back in shape.

Next grab the wire with pliers and put a 90° bend in it such that it aligns with the second hole in the side. You want to make the side section just a little too short so that it keeps the loop/arm/bottom section from being loose where it joins onto the body. This may take a few tries to get the bend in just the right spot. Then put an arc with a radius that approximates the side length in the end of the wire and feed it through the hole.

I found it easier to proceed to the next step on the same side before coming back to the other side.

Step 8: Wire: Tips

While pushing the side wire tight against the outside of the body, grab the end and bend it outward. Make this bend as sharp as you can so that it locks the wire in place. Then straighten it back out to run parallel to the sides of the bottle holder.

Go back and finish the other side up to this point, then compare the two ends to make sure that they're the same length and trim one of them if needed. You don't want any sharp points, so round the ends of the wire with a file.

Then grab the ends with pliers and curve them under. This will make it easier to get the bottle into the holder and will also keep the cyclist from getting poked. And it makes the bottle holder look a bit like a butterfly, which is entertaining!

Step 9: Finishing Up

It should now look like a bottle holder!

Try the bottle you plan to use in it and adjust the wire to produce a tight fit so that the bottle won't rattle or fall out. The angle of the tips, the height of the loop, and the angle between the bottoms can all be changed to produce dramatically different fits.

Finally, if you have a cat, make sure it approves of your work!