Introduction: Pro Tips for Using Cardboard

About: Arduino and Robotics Nerd, and alumni of FIRST Robotics Team 5683 (Go R.A.V.E.!). Blinking LEDs with Arduino is still one of my favorite pastimes even after years of doing it.

Corrugated Cardboard is an extremely cheap, plentiful material with great structural properties that makes it perfect for DIY projects around the house. I also use it so much that I have come across some very useful tips and tricks for using it, and that is what I will be showing you today. These are all learned from experience, so you had better bet they are tried-and-true methods for success.

In this Instructable, you will learn:

The best ways to cut cardboard,

The dos and don'ts of gluing cardboard,

How to structurally reinforce cardboard,

How to give cardboard a professional-looking paint job,

And finally, one crazy trick for getting rid of those pesky frayed edges.

If you like this or learn something new in this Instructable, please vote for it in the Pro Tips Challenge. I'm getting kinda tired of using cardboard all the time (despite its many uses) and that 3D Printer looks like it could be a good upgrade... (-;

Step 1: The Best Ways to Cut Cardboard

Well, this should be easy. Just get out a good pair of scissors, right? Nope, wrong. Using scissors is one of the most infuriating methods I have come across for cutting corrugated cardboard. The exception is for small, straight cuts. Here are some better ones:

Method 1: X-Acto knives

Using an X-Acto knife or a decent box knife is my go-to method of cutting cardboard. First, trace out what you want to cut with a pencil, and then score it with the knife. The best method is to make multiple (2-4) passes, cutting a little deeper each time, until you cut through. This is best for small cuts and detail work, although I have used it to cut large pieces before, but beware of hand cramps. Also, try to cut on top of a surface you don't mind getting a bit scratched, i.e. another piece of cardboard.

Method 2: Hacksaw/ Reciprocating Saws in general

For thicker cardboard, e.g. double layer cardboard, or large cuts, using a saw actually works really well, and is the best, fastest, and most accurate way to cut. I find a standard mini hacksaw is my favorite tool for dealing with this stuff, but any saw with a reciprocating blade (Scroll saw, band saw, jigsaw, heck, even a sawzall) will work fine, provided you know how to use them. In this manner, cardboard can be treated generally the same as wood, and many of the same tools you would use for plywood (except the planer) are perfectly acceptable for use on cardboard.

Method 3: Laser Cutters

I won't go into much detail, as I have less experience in this area, but for really complex designs or nice cutouts, a laser cutter is the best choice. It can do everything you could do with any of the other tools I've mentioned a lot faster and a lot more accurately than you can by hand. The only thing to watch out for is not catching the cardboard on fire!

Method 4: Soldering Iron/Pyrography

This method is a bit whimsical, dangerous, and not really accepted as a practical method for cutting cardboard, but man, is it fun! If you have an old, useless soldering iron, or a pyrography kit, this is a great and entertaining way to cut cardboard. Simply heat up your iron, and use it to burn through the cardboard. This is best done outdoors or in a garage, because it will set off fire alarms if you are doing it for a longer period.

So now you know how to best cut pieces of cardboard, and we can move on to the best ways to glue them together!

Step 2: Dos and Don'ts of Gluing Cardboard

"Any old glue will do" is not really a good philosophy for gluing cardboard. Here are some tips for gluing with different types of glue:

Edit: There are many kinds of glue that I haven't mentioned here, including tacky glue, rubber cement, and wood glue. All of these work perfectly well on cardboard and each have their own individual strengths and weaknesses, but since I haven't used them in a long time I have decided to leave them out of this Instructable. Thank you to those of you in the comments section who have reminded me of the existence of these glues!

Hot Glue:

By far my favorite way to glue cardboard, Hot Glue will stick to almost anything and can be used almost anywhere. It is best used to glue large pieces together permanently, but is terrible for use with paint. Hot glue is also good for filling gaps. If you want a good joint, I suggest putting down a thick stream of glue and pressing together, and then running the tip of the glue gun over both sides of the joint while ejecting a steady stream of glue, similar to the technique used while caulking molding. You will need to use patience while the glue cools, but keep in mind it's still a lot faster than most other glues.

Another tip: Black hot glue for some reason works better than the clear stuff; it sticks and flows better, and doesn't string up as much. I recommend using it if you hate all those little hot glue strings all over your projects.

Elmer's Glue:

Best for small parts or areas that will need painting, but won't work for edge joints. I don't use this glue much, but I keep it just in case.

Glue Stick:

Good for use when gluing cardboard to paper sheets or foil. Infuriating because it dries too fast on paper and too slow on foil, this glue is rarely used in my workshop, so I don't generally keep it on hand.

Cyanoacrylate (CA Glue) and Super Glue:

I hate this stuff. It sticks to my fingers, and won't form a good joint with cardboard (unless it's with my fingers). My advice? Avoid if at all possible.

Now you know how to glue cardboard properly, so let's move on.

Step 3: How to Structurally Reinforce Cardboard

Too thin? Too flimsy? Bends in all the wrong places? We can fix that! Here are some ways to reinforce cardboard to expand it's usefulness (these are my own personal names for the methods, by the way):

Double-Layering, Crosshatched Style:

This method is good if your cardboard is flimsy, thin, and bends where you don't want it to. Simply take two sheets of cardboard, and glue the faces together so the "grain" or direction of corrugation in the first piece is at a 90 degree angle (is perpendicular) to the "grain" in the second piece, creating an internally crosshatched structure.

The Industrial X-frame:

When you need your cardboard to be structurally stable at all points, e.g. for a shelf, making an X-frame with cardboard strips through the center from each corner is often the best way to do it. See the pictures for an example.

The Box-Frame:

This method is best for open frames, where two sides need to be spaced apart but still aligned and stable. Simply cut rectangular standoffs from cardboard, and glue them at evenly spaced intervals on each side.

There are other methods of reinforcing cardboard that I haven't mentioned, but these are my favorites and also the only ones I've ever needed to use, so they are the only one's I'll list here. Now we can move on to how to get a nice paint job with cardboard.

Step 4: Paint Like a Pro... With Cardboard!

Painting things is what really sets your projects apart, and where your skills for aesthetics really shine. But on cardboard, that brilliant paint job just doesn't seem to turn out! Here are the best ways I've discovered to paint nicely with acrylics on cardboard.

1. Use a backing or base coat.

The best way to get colors to show up is to paint a layer of white, beige, or light grey paint onto the cardboard before you start with the rest of the paint. This allows your colors to shine vibrantly, so that you almost can't tell it's cardboard. Another way to do this is to paper mâché over the cardboard with white paper, or just gluing sheets of printer paper on as a backing layer, essentially creating a sort of wallpaper on your project. Beware of wrinkles when painting on this!

2. Matte and Gloss

Different paints work differently, and the real differences you want to watch out for are between Matte and Gloss paints. I usually mix the two so that I get a semi-gloss, and this is fine applied directly to the cardboard (for a more rustic or weathered feel/look) or with a base coat (for a newer look).

Matte paints are usually pretty thick, and are generally fine without a base layer. However, gloss paints do much better with a backing layer, as sometimes they can be watery, and the gloss loses some effect on the matte surface cardboard.

Use gloss to get that brand-new look, and matte for more industrial, weathered, or earthy aesthetics. Sometimes, using both side-by side can be used to highlight certain features, but make sure that you don't make it look too tacky.

3. Some notes on Brush Type, Size, and Shape

For sharp lines, I use medium size nylon brushes with a flat, wide head. (I think it's called a "chisel" brush.)

If I am covering a large area, I use a large brush, again with a wide flat head.

For matte paints, softer brushes are better, but you lose some detail, so I go with medium-soft brushes for most purposes.

Round brushes are good for small detail, but not for large areas.

Tiny brushes are useless for most things cardboard, I only use them for watercolor (which I don't use on cardboard).

Now you should be set to paint on Cardboard!

Step 5: And Now We Will-- Wait, Is That a Frayed Edge? Get Out! GET. OUT. No Frayed Edges Allowed!

When cutting cardboard, especially with a saw, "frayed" or rough edges are common and extremely annoying. I have a simple trick for getting rid of them, which I don't think many people would think of normally... But desperate times *cough*f-frayed...e-edges*cough* called for desperate measures.

So my trick is... (drumroll please): 80 grit sandpaper. I know. Boring, right? Just sand the frayed/rough edge like you would with wood, and it will soften out very nicely, making your end product much better.

I could go on for ages about how great this is, and different sanding tools and techniques, but I'll let you discover those yourself. This is a DIY community, after all, and I can't tell you how to do everything...

BTW, If you've never heard of this trick before, scroll back to the first step and click that "Vote" button. Did that already? Good, let's move on!

Step 6: The Grand Finale

So now, I've basically outlined all the tricks I know for using cardboard (okay, so maybe not all of them, but most, anyway). Above are some images of stages that utilize cardboard in past projects I've done here on Instructables, just as inspiration for all you out there just discovering the many uses of Cardboard.

*Entering speech mode, clears throat, and begins in a deep, clear voice* (Just read the bold if you don't like speeches.)

I challenge you, yeah, YOU, the person reading this who lives on the planet Earth and has access to cardboard and is going to click the Vote button if you haven't already, to go out and use these Pro Tips, Tricks, and Skills to better the world around you, to create without end, and to ultimately improve and hone your abilities until you find you can imagine what 5 minutes ago was unimaginable. Because you can. No, not a soup can, or a beans can, or a trash can, just CAN. And if you think you can't, you won't or you bottle, then I believe you will find a time sometime soon in the very near past where you are wrong. Just go out, and CREATE, just for the sake of creating if nothing else.

Okay, that's all I've got. Speech over. My fingers are numb from typing. Maybe I'll record that and add it as a video so your eyes don't go numb from reading, too.

I hope you enjoyed this and/or learned something! Please comment if you have questions or suggestions!

As always, these are the projects of Dangerously Explosive, his lifelong mission, "to boldly build what you want to build, and more!"

You can find the rest of my projects here.

Happy Making!

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