Alternate assembly techniques

Cutting slots in cardboard gives you an easy way to assemble pieces together. Cut the slots slightly narrower than the thickness of the cardboard. Once slotted together you can add glue.

Another way to make strong joints and seams is to cut only through the top layer of kraft paper and the corrugations, leaving the bottom layer of paper uncut. Then you can fold it like we have done with the pyramid here.

You can insert wire directly into the corrugation flutes then attach cardboard pieces together. This can be very useful for angles. And with soft wire it can act as a functioning hinge.

Hardening and preserving your cardboard projects

Shellac is an excellent product for preserving and strengthening cardboard. It is similar to varnish but it is an all natural and non-toxic product made from the excretion of lac bugs.

Apply it with a paint brush and let it dry. Apply multiple coats for a stronger covering. It will make your cardboard projects more durable and water-resistant.

You can also shellac the inner sections of your project. This will further strength and protect it.

Note that shellac, when it dries, is non-toxic and hypoallergenic. But, applying it is not for kids. It can be messy and it does have alcohol as a suspension agent. And it is a type of stain so it can stain other objects such as furniture and clothing.

Mod Podge is another excellent way to seal and protect your cardboard creations. It is also more user friendly and readily available in every store that sells arts and crafts supplies.

It comes in a wide variety of finishes including matte, semi-gloss, gloss and high gloss. It even comes in a spray can.

Using mod podge will seal and protect your projects and it will preserve the brightness of the colors.

Primer and Paint

You can use arts and crafts paints to paint your projects but because of the deep brown color of cardboard and how readily it absorbs paint I recommend you first prime everything first with white paint. This will give you richer colors when dried.

And I suggest you seal it afterward.

Quick tip on how to get nice and sharp corners and edges with cardboard.