I love the airport, and it's not even because of the planes (no offence to pilots). It's because of the countless conveyor belts they have there. Check in your bags? Conveyor belt. Need to get to your lounge fast? Conveyor belt. The best one of all is when you go to pick up your baggage. How they manage to make a round conveyor belt is beyond me. With that aside, I've decided to make a simple marble run with a rubber band "conveyor belt" that carries marble up and lets them roll down, and repeats it over and over, and is quite fun to watch. (This seems like a easy enough project that could be done in a classroom setting!)
Let's get started!

Supplies

This project takes about an hour to build. You'll need:
- Cardboard

- A hot glue gun

- Straws

- A ruler

- A LEGO power functions motor (optional)

- Lego tape (goes with the above mentioned motor)

- Rubber bands, preferable thicker ones

- Hardboard

- A scroll saw

- Miscellaneous marble run building stuff

Step 1: Base Part 1

Using the saw, cut out four 1x1 inch squares, and drill holes in 2 of these. The holes should be snug for a straw, but will still let it spin freely.

Step 2: Axles

Cut out a 9 centimetre bit of straw. Now, cut out another piece of straw about 1.5 centimetres longer than the first one. Then, cut out a piece of skewer a few millimeters longer than the short straw.

Step 3: Base Part 2

Now, pay attention to this step, because it's the hardest part. Take one of the squares (without a hole) and glue the skewer to the center of it. Cut out 2 strips of cardboard, (Mine were 1x5 inches, but the size of your rubber bands will vary) and glue the square to one strip. Slip the shorter straw onto the skewer and out the rubber bands onto it. Then, glue the other side of the skewer to the other square without a hole, and glue that to the other strip of cardboard. Put that aside. Thread the 2 squares with holes into the longer straw, and glue the 2 squares to the other end of the 2 cardboard strips. The rubber bands can be slipped onto the other straw now. I've glued a green straw to one end of the red straw to keep it from falling out of the square, and on the other end, you can attach a crank, or as I've done, a red LEGO bushing.

Step 4: Scoops

The belt can't carry marbles up if it doesn't have anything to scoop them up!
Build a shape like this out of cardboard. The thickness should be a little less than the diameter of your marbles. Glue this shape to the Conveyor belt. The number of scoops is up to you! For a relatively slower pace, I've decided to use 2.

Step 5: Motor (Optional)

If you decided to use a motor, it can simply be attached to the bushing you put on in the last step. A gear system may be used if you'd like the conveyor belt to go slower. At this point, you can use the conveyor belt for other things, like passing the salt to a person 5 inches away from you, but keep going if you want to build something way cooler.

Step 6: Slope

Letting the conveyor belt sit down flat and making it chuck marbles down a track seems like a fun idea, but it's not what we want right now. To make it carry marbles up, cut out a piece of cardboard and glue it down so that it sits at an angle. A 45 degree angle is good enough, and I recommend it, but again, you could modify it to take marbles straight up!

Step 7: Power Plant

This is the electric part of the loop, the one that'll keep the marbles going. Build any shape, but it needs to have 3 areas:
- A spot for the conveyor belt
- A spot for the battery box
- A spot for the motor
I've mounted the motor onto the cardboard with LEGO tape to avoid getting hot glue into the holes, but everything else can be hot glued to the base without any problems.

Step 8: Build the Frame!

This is the fun part!
Take your marble run building supplies and build a loop for the marbles to "run" on. I just built a simple track, but this has endless possibilities. Maybe make a pinball machine. Maybe attach another conveyor belt to it! Just make sure that the ball gets back to the belt so it can do it all again.

Step 9: Finished!

You're already done! Congrats!
Here's a video of mine, with the aforementioned gear system to slow it down a bit.
It was fun building this, and it's sitting on my shelf giving marbles rollercoaster rides right now.
I'm thinking of building more marble loops, and attaching them to make a big marble run. We'll see ;D

See you around!