Introduction: Cardboard Chassis for Cheap Robots 1: Boxbot

About: I build robots out of boxes! I love teaching what I've learned and seeing people add their own ideas to what they've learned. Nothing excites me more than seeing a student really take an idea and run with it!

Previously I made an Instructable on cheap motors and wheels for robots, but wheels alone don't make a robot. If you want your robot to cruise in style, it's going to need a sturdy and stylish body.

It's easy to make something rough but functional, but in my experience taking the time to make something look good usually makes it work better in the long run. A clean design makes it easier to add features, swap out parts, and generally keeps you from going nuts. That's why I'm not just focusing on the design of the body, but how it looks as well. That's right! No cobbled together duct tape monstrosities for us!

This is going to be my first Instructable in a series that will show you how to make several different cardboard bodies for your robots. I had originally intended to mash them all into one, but found that the steps for each were more extensive than I had originally thought. In order to keep these Instructables short and understandable, I've decided to break them up into several.

Now, break out the card board and plug in your hot glue gun. It's time to make a cardboard robot chassis!


For more Instructables on building cheap robots, head to the For Cheap Robots collection, or for more things that I've done, check out my profile page!

For more info from Digilent on the Digilent Makerspace, check out the Digilent blog!

Step 1: The Box Is Always More Fun

If you're anything like me, you probably have a couple of old boxes laying around the house for no particular reason. They seem to nest and multiply in the dark, unused corners of my apartment. Oh sure, I always keep them just in case I need a box to ship things in, but I hardly ever send anything larger than a letter through the mail, and flat rate boxes are so much less hassle.

Why not put that box to use? It's sturdy and simple, which makes it prime robot building material!

Step 2: What You'll Need

For this project you'll need:

  • A small box. I got one with a lid, but you don't have to. As you'll see later on, the lid complicates things, but it'll also act as another place to put stuff like arms or antenna later on.
  • Robot guts. I use a DP32 because it's cheap and powerful, plus it's got a breadboard right there, so you can connect simple circuits right to the board.
  • Battery pack. Four AA or AAA batteries will work best for most microcontrollers.
  • Motors. I think we'll need these later.
  • Bottle cap. This will become a sort of third wheel to keep our robot stable.
  • (optional) Breadboard. This can come in handy if you just want to test circuits out, but don't want to solder them just yet.
  • X-Acto knife. These are dangerous, so kids will want to get an adult to use this for them, so they don't hurt themselves.
  • Hot glue gun.

Not pictured are:

  • A roll of duct tape.
  • Pen, pencil, or marker.

It's worth noting that I've included both direct-drive motors with duct tape wheels and gearbox motors with bottle cap wheels. If you haven't already read it, my previous Instructable can show you how to make these. In this project, I'll show you two different mounting methods for both of these wheel types.

Step 3: Adding the Third "Wheel"

Let's start by adding the third bottle cap "wheel".

Flip your box over onto it's back to get access to its underside. Now add a small strip of duct-tape to the back middle of your robot's underbelly. Finally, glue your bottle cap to the duct tape with a couple beads of hot glue. You don't need much to keep it on, and using less glue will make it easier to take off if you want to replace it later on.

Step 4: Mounting Your Motors: Direct Drive With Duct Tape Wheels

Direct drive motors are the easiest motors to mount.

Flip your box over again, and add an approximately square piece of duct tape to the front face of your box, in one of the lowermost corners. This will be where we mount our motor.

Wrap your motor in duct tape. This will make it easier to remove from the box if it breaks or we decide to replace our motor with another.

Before you glue, you'll want to check your motor's placement and angle. I had forgotten to do this, and had to re-do that step, so you can learn from my mistakes. The key think you'll want to keep in mind when deciding on a good angle is that the tip of the wheel has to be lower than everything else so your robot rests on the wheel and not the underside of your box or one of your motor's corners. You also want to keep your motor at an angle so the wheel can roll and not just spin in place.

Now that you know what angle you want your motor at, glue it on! Keep in mind, you don't need very much glue to keep the motor in place, and the less glue you use, the easier it'll be to pull the motor off when you want to replace it.

Do this for both sides, and you've got your motors mounted!

It's worth noting that you can use this mounting method for both direct drive motors and geared motors. The only difference is what angle you mount the motors at. However, This method leaves the robot looking a little rough, with it's motors on the outside and wires hanging everywhere. Next I'll show you a cleaner method that doesn't leave so much out in the open.

Step 5: Mounting Your Motors: Geared Motors and Bottle Cap Wheels Part 1

Before we begin, I'd like to point out that this method is more involved than the previous method, and also uses an x-acto knife. If you would rather avoid any of that for whatever reason, the previous method will work just fine.

Start by marking the width of your motor against the side of your box. Hold your motor up to the side, towards the front where you'll be mounting it, and draw two lines on either side to indicate its width. You can use this to make your hole wider than your motor. I would recommend about an eighth of an inch or 3 millimeters.

BE CAREFUL USING AN X-ACTO KNIFE! Especially when you're punching through to the other side of a piece of cardboard like this, it's easy to slip up and cut your finger or stab your hand. I have a couple scars myself from doing this as a child, so trust me when I say it's not fun. If you're a child in grade school or middle school (under approx 15 years old) please get an adult to cut these holes for you. If you're older than that, be extra careful and keep in mind to keep your fingers clear from where you're cutting.

I would also recommend cutting your hole higher than you think you'll need. When I cut mine, I had to go back later to fix it, because even though my motor fit, squeezing it into the hole made it nearly impossible to glue in. Check to see if your hole is large enough by fitting your motor through, and if you can't slip it through with a lot of wiggle room, cut it larger.

Now you'll want to measure your hole so you can cut a hole of the same size in the other side. Because I had saved the pieces I punched out of my first hole, I could use these to measure out what size my hole should be.

As an additional note, if you have a box with a lid, you'll want to take a moment here to close your box and see where the lid interrupts your hole. If you trace it with a pencil, you can trim your lid now. I didn't realize this would be a problem until later (as you'll see in part 3).

Step 6: Mounting Your Motors: Geared Motors and Bottle Cap Wheels Part 2

Take a moment to wrap your motors in duct tape. Like I said before, this will make it easier to remove your wheels later if you need to fix them, or replace them.

Take a strip of duct tape and either cut it or tear it in half. Save both pieces because you'll use them. Slip one piece through one of your motor holes. Make sure to leave a little bit hanging over the edge (at least half an inch or one centimeter). When you press the tape down, fold this overhanging bit under. This will protect the bare edge of your cardboard hole from getting stuck to the hot glue.

Now, put a stripe of hot glue down along your strip of duct tape. This is one of the few times when I would recommend using a lot of hot glue. About twice as much as I show here should do the trick. Because the motor is laying on top of the cardboard it's mounted to, the upward force from the motors is actively trying to peel the motor off the duct tape, so you're going to want some extra sticking power here. Hence the extra glue.

When you put your motor through the hole, slip it in at an angle so it doesn't smear the glue you laid down. Then press it down and hold it until the glue sets. Finally pull the wires through, and repeat the process for the other motor.

Step 7: Mounting Your Motors: Geared Motors and Bottle Cap Wheels Part 3

This step is optional, depending on whether or not your box has a lid. As you can see in the pictures above, my motor interfered with my lid so it couldn't close. I took a moment to trim my flaps so they wouldn't hit my motor.

Step 8: Where's the Robot Filling?

(The rest of this project assumes that you used the first mounting method for direct drive motors with duct tape wheels, but the principals still apply to robots with gearbox motors.)

Just because we've got our motors mounted, doesn't mean we're home free just yet. We don't want our parts rattling around inside our box while our robot drives around. Imagine if your guts rattled around inside you when you walked. Not fun. Let's get those parts glued down.

You're going to want to start by placing a strip of duct tape down wherever you want your parts to go. When I put my breadboard down, I checked to see how it would fit with my DP32 and battery pack first, before putting its strip of tape down.

Put some tape on your parts next. Tape will come off more easily than glue. You don't have to completely cover their undersides with tape, so just use enough. In fact, I made sure that none of my tape would hang over the ends because it looks better. Now put some glue on your parts (not too close to the edge of the tape, and not too much) and press them down.

Step 9: Finishing Touches.

These steps might now apply to you, depending on what kind of box or motors you used.

My motor's wires were very long, and while this made it very convenient to connect them to my breadboard, once the lid was closed, they would stick out and flop around all over the place. I fixed this by putting a little bit of tape on the inside of the lid to keep them restrained.

Because my motors were attached to my box's lid, I needed a latch to keep it closed, so I fashioned a simple one out of a couple pieces of duct tape.

It's important to make sure that all your loose ends are tied up, so they don't get in the way when you're testing your robot for the first time.

Step 10: The Most Important Step: Make It Your Own

I'd like to introduce you to GORMATRON! The Dragon Princess!

One of the biggest draws to making a robot is the chance to make it uniquely yours. To my mind, this is one of the biggest draws to using cardboard, because it affords us a lot of space to play with our creations. I don't just mean aesthetically either! You can play with functional additions as well. Try adding a motorized arm to your robot, or maybe a rubber band gun!

I want to see what you guys (and girls... and anyone else for that matter) can do with this stuff, because that's where you'll really learn. Go nuts!