The shop wanted $50 a wheel to change out the bearings.

The internet wanted $60 for the tool to do it.

I knew there had to be a better way.

The official name for this tool is a 'mandrel bearing puller.'

Step 1: Materials and Tools

Materials
1/2" Button head machine screw, at least 1 1/2" long, available at any hardware store
Flat head screwdriver with a somewhat large head and an impact resistant handle (this may get destroyed)

Tools
-Drill
-Hammer (any type, even a rock will do)
-File or belt sander to speed things up
-Hack saw, or band saw to speed things up
-Some sort of clamping device (vice)
-Safety goggles for power tools and hammering

Step 2: Shape the Head

Mount the bolt in the drill chuck.

While the drill is spinning, use the belt sander or file to shape the head until it just fits through the inside of the bearing . Profile it to have a narrow edge, like an umbrella. The edge allows the tool to fit into the chamfer (space between the bearing and spacer) to grip the bearing.

Step 3: Cut

Now cut the bolt lengthwise, through the head and down most of the shaft, leaving about 1/4" uncut.
I used a horizontal bandsaw, but a hacksaw and some elbow grease should do the trick.

Bend the two sides away from each other just SLIGHTLY by pressing the screw driver into the slot.

Step 4: Make a Handle

This probably wasnt necessary, but I made a handle with a bolt, a lot of washers, and a nut. The tool threads into the other side of the nut.

Step 5: Using the Tool

To use the tool, insert the bolt head side of the tool into the bearing until you feel it reach the indentation on the other side of the bearing.

Next, press the screw driver from the other side of the wheel into the slot in the bolt head. Tap the back of the screw driver lightly with a hammer, and then harder to drive the bearing out.

Repeat for the other bearings.

DISCLAIMER: THIS WILL DESTROY THE BEARINGS. NEVER APPLY FORCE TO THE INNER BEARING RACE WHEN TRYING TO SEAT THE OUTER BEARING RACE OR VICE VERSA. THIS DESTROYS BEARINGS. DO NOT USE THIS TOOL TO INSTALL NEW BEARINGS.

Destroying the old bearings doesn't matter as the whole reason to remove bearings is to replace them.