Taping inside corners on cardboard

Does anyone have a good way to apply tape on inside corners? (Not drywall, for which there is lots of info on the web...) I like to cut down cardboard boxes for specific spaces and often need to join two cut  sides to make a corner, and would like to use duct tape or packing tape on the inside and have it look half decent...

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Assuming corrugated cardboard here and not the thin stuff from cerial boxes and similar....

A really nice way to create boxes just from cardboard sidewalls was "invented" by myself when I was a kid ;)
Had no clue on how design a box with flaps to glue so I substituted like this for boxes that had to look really good from the outside:
It requires the walls and bottom parts to be cut so they match up on the inside.
1. Take cotton yarn or similar of good thickness - if in doubt try packing cord but nothing synthetic.
Dilute some wood glue, with about 10% water and soak a lenght of about 3m yarn.
You might need to use maual labour here to get the air out of the yarn as you need really need it fully soaked through.
Pull the yarn through your fingers to remove as much access glue as you can and to get a smooth finnish.
With good tension hang it out to dry - I used 3m as it was a nice fit betwenn fence and a clothes line post.
Let it fully dry until the yarn is hard and stiff.
2. Prepare your box walls:
Place them together and mark matching points in the corners and along the wall.
Like alignment marks if you will.
This will be used with the prepared glue string!
Check on a spare piece of cardboard if your string is strong enough to punch through the cardboard - if not find a suitable tool of similar thickness to do te job.
3. Prepare the yarn:
You want to use the glue string as an angle bracket of sorts to join the walls together.
This means you cut pices of suitable length but at least 2cm long.
With a low heat flame, like a candle, heat the middle of the yarn - you will fell it going soft.
Bend in a 90° angle and put at rest to cool.
It helps to have a metal plate for this that was place in the fridge, a glass mirror will work fine too.
4. Mounting fun:
Punch holes through the corrugated center where required, use the space in the pattern where you can - if required make sure to make a new alignment mark on the other wall!
Add a small amount of wood glue into the hole - wipe off acess.
Do this for all holes along a wall you need to mount.
Place the glue angles into the holes and slide the wall into the other side of the angle.
You might need a bit of wiggling if your holes are a bit too small.
5. The other walls:
After the first wall is done and the glue had a few minutes to set you do the same with the next wall until you have them all together.
Place the glue angles into the bottom part of your box as before with the walls and then place the already joined walls onto them - it really helps here to have a second pair of hands you can borrow for a few minutes.
Once all is in place do a last check that there are no gaps, fix all in place and let the glue dry.
6. Finnishing touches:
Cut paper strips about 2-3cm wide and as long as the joints of your box - plus 1cm extra.
You can use packing paper for a similar look or colored paper to highlight the corners.
Fold the strips in hlaf lenghtwise to form the corners of your box.
Use diluted woodglue or wall paper glue (if you have it) to attach the paper strips over your corners after wetting them with glue.
If in doubt good craft glue will work too but the stuff tends to dry too quickly for longer strips.
To get the excess over the cornes to the inside or under the bottom you will have to make some cuts with a sharp pair of sissors - you will see where by the bulding or you can do some testruns on that on spare pieces first.
If you want to cover the inside cornes too it is best use two smaller strips that line up in the corner.
You can slightly overlap the first and then place the second over it in the same way you would do with wallpaper in your home.

Using good paper these boxes are surprisingly sturdy and stable when finnished and the glue strings make it next to impossible to break the seems with normal usage.
Modern hint:
Instead of glue strings you can now substitude with 3mm PLA 3D printer filament (needs a bit of sanding to get a rough surface) or even PVA based filament that binds directly to the wood glue.

If the crease of your corner is vertical, place a piece of tape horizontally, as many as needed to make it stable, then to make it clean place a piece of tape vertically and flush to the corner. It's best if you have a long enough vertical piece to fold over the edges of the cardboard. If your crease is vertical, switch the words Horizontal, and Vertical.

This is what works for me.

dragon fllyer (author)  Nemesis-Perilous19 days ago

Hey, thanks - I hadn't thought of that, but it should make the tape a lot more controllable than the longer pieces I've been trying to use. I'll try that on my next cardboard box rebuild!

Does it matter if tape on the inside of the box looks ugly? After all, the inside of the box gets looked at less often than the outside.

Also, in the past, I have used glue, the so called "white glue", also called PVA,

https://en.wikipedia.org/wiki/Polyvinyl_acetate

for gluing one piece of cardboard to another, for to make a seam in a cardboard box.

Actually that re-glue job, was not for a re-sized cardboard box. It was for a turn-the-box-inside-out job. This particular cardboard box was covered with ugly, glossy, garish, advertising, and I wanted to turn it inside-out, so the outside appearance of the box would be plain, brown, cardboard, instead of ugly advertising.

The main drawback with glue, besides it being complicated, necessitating some flat pieces of wood and clamps to squish the seam together while the glue dries, is that it takes time for the glue to dry.

In contrast, the advantage with using tape, is it takes less time and effort, and you can use the box right away.

Yonatan2420 days ago

I used zip ties. I found that regular tape peeled off after 5 minutes.