Rubber Band Powered "Hot Wheels" Type Car Launcher

Ever wanted your toy cars to really go? Wanna new way to race? Want an excuse to build something really cool for your kid? Or do a fun project WITH your kid? You don't have to go buy a new cheap plastic toy, make your own fun from leftovers from prior projects!

This is a not too complicated project that easily modified to use materials you have on hand. For ours we used scrap wood, scrap plastic, and a rubber band from an asparagus bunch! It does require basic carpentry skills, but nothing too usual or complex. You'll notice there are a lot of steps in this instructable, that's mostly because I was trying to be thorough, so don't let it scare you.

This prototype is a single car launcher, but could easily be modified to launch 2 cars at once for racing purposes... that will probably be the next project! It also is designed so that you can attach it to your hot wheels tracks (not shown here).

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Hope you enjoy!

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Step 1: Materials

Most of this was just scrounged around our basement. After reading through the instructions, feel free to attempt substitutions if needed.

You'll need:

A few Hot Wheels, Matchbox, or similar cars to ensure size and for testing.
Block of wood, taller/longer than your cars.
Short screws (4 top, 4 bottom, 6 sides)
4 finishing washers (optional)
I eye screw
Scrap plastic as wide as your wood block, and a few inches longer (or stiff cardboard, or thin wood, or even an old circuit board!)
Scrap clear stiff plastic (either recycled from some packaging, or lexan, or even shrinky dink material) about the size of your wood block.
Rubber bands (at least one, various sizes are nice) We used one from some asparagus.
String or twine (optional)
"Bumpers" (little rubber/plastic feet) for the bottom (see step 11)

Hardware requirements:
Saw for cutting the wood
Sandpaper
Pencil
Screwdriver
Dremel or Drill
Business cards or other similar scrap cardstock (try junkmail!)
Utility knife
Straight edge
Sharpie/marker (for marking plastic)

Step 2: Measure and Prepare the Wood Block

Ensure that your wood scrap is slightly taller than the tallest car you want to use (pic #2), and slightly longer that a typical car. Cut down if necessary. (Ours was 1.25 in tall, and about 3.5 inches square.)

Find the center of your block, and using a car as reference (centered on the block), mark just outside of each wheel.
(see pic 3)

After you mark the car's width, remove the car. Use a pencil and straight edge to draw reference lines for cutting. Ours were about an inch in from either side of the block (see pics)

Step 3: Cut Your Wood.

Make 2 cuts, along the lines from the previous step. Now your wood is in 3 pieces. The two sides will hold the car in place, and the middle piece will be the one that moves to launch the car.

(Any kind of saw will work for this, even a handsaw, just takes longer!)

Step 4: Cut Out the Bottom.

Reassemble your 3 pieces of wood (you may want to mark top/bottom/sides so you can remember what goes where), and use them to measure out a bottom for the launcher.

We used a scrap of stiff plastic, about the thickness of poster board, but anything stiff and thin like that would work. Measure around your wood block to figure out the size, sketch onto the plastic, and cut with a box cutter knife.

Leave extra on the front (2-3 inches) for a 'loading ramp'.

Note: You'll see the lines on the front of our loading ramp labeled 'tongue'. Although we currently have no actual Hot Wheels tracks, we wanted to ensure this would work with a store bought track when we got one. Should we at some point get a track, we will cut off the 'loading ramp', and cut out a piece of it to be a 'tongue' (or 'connector') which can then be glued under the laucher, to connect a standard hot wheels track.So we left a "tongue" which can be inserted into the underside of a track to attach the launcher.

Step 5: Attach the Bottom

Pic 1: This is what it will look like when you follow the below steps.

Pic 2
1. Place a few business cards between each piece of wood, for temporary spacers (unlike the picture, rip or cut them in half so they don't show and get in your way.
2. Place your bottom on the blocks, and mark where the pieces come together with pencil.
3. Use a straight edge to transfer those marks to the plastic. Mark where you want your drill holes about 1/2 inch in on each corner of the bottom (centered on each of the side rails)
4. Using a Dremel or small drill, drill pilot holes.

Pic 3
1. After all your holes are drilled,
2. use screws to attach the bottom.
3. Realize that you have a power drill, why am I doing this by hand??
4. Remove the spacers, and ensure the center piece moves freely.

Step 6: Attach the Rubber Band Guide Screws

First, mark the center of the side of the block, drill a pilot hole, and partially screw in a short screw.
Repeat for the other side.
These will be used to hold your rubber band.

If you like, you can add more screws, to give different levels of tension or for different size bands. We ended up with 3 on each side.*

On the back of the Center block, mark the very center (pic 4) and screw in a small eye screw.

See pic 2 for what it should look like now.

*(Note: we weren't sure at this point if we were going to take off the corners of the block. (as is marked on top in pic 2) We ended up deciding it would work better that way, so we did that later in the steps. You don't have to, but if you think you want to do the same, make sure you don't put screws up there!)

Step 7: Attach Rubber Band and Check It Out.

You're not done yet, but check to make sure everything is working thus far.

Insert your rubber band in the eye screw, then slide the ends over the side screws.

When you pull back on the eye screw, the center piece should slide smoothly in and out.

It was at this point that we decided to a) add more screws so it was easier for a child to operate and b) to take the corners off.

Step 8: The Clear Top (attempt 1)

The original idea was to use faux shrinky dinks to make a clear, decorated top for the launcher.
We had a large #6 plastic lid, so we colored flames on it with sharpies (because flames are cool!) and shrunk it. ( See here for instructions on doing this .

Unfortunately, this particular piece of plastic did not shrink up evenly--and shrunk unusually small! That's not to say that this idea won't work. It's worth a try, but be aware, unless you buy the real shrinky dink sheets, it's hit or miss how much your plastic will shrink, and really big pieces can stick together and wrinkle.

So see the next step for what we actually ended up doing.

Step 9: The Clear Plastic Top (final Version).

Pic 1
We used scrap Lexan. Any sort of stiff plastic will work.
Measure your size to match the top of the block. Mark with Sharpie. Score. Snap.

Pic 2:
We have the approximate size.
Take the rough cut piece of plastic, hold it up to your blocks, and mark around it with a Sharpie.
Use a sander/sand paper to file down to the lines marked.

Pic 3:
The finished top.

Step 10: Attach the Clear Top.

Similar to the bottom. Measure in from the sides. Drill your pilot holes. Drill the hole in the plastic LARGER than the screws, so it doesn't crack the plastic. Screw in screws.

(The washers used here were for looks only. They are "finishing washers". If you have them, use them, but they are not necessary.)

Wow! You're pretty much done!

Step 11: Final Touches!

So it doesn't scratch your surfaces, we added some glue on 'feet' on the bottom.

For ease of sliding, a candle rubbed along the sides of the center bar makes sure things run smoothly.

You're ready to load it and test it out!

Step 12: Launch Some Cars!

Attach your rubber band as in step 7, pull back the eye screw (we added some twine tied to the screw to make that easier).

Put your car in the slot, and let go!

The car shoots across the floor.... Yay!

Instruct small children in the care and handling (leave it on the ground! no pointing at people!) and let them go to the races.

Hope you enjoyed this... I'd love to see other versions of it too... Like a double car launcher for racing!

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