Thick Card - Ways to fold it properly

To get around the card thickness being too much I tried two ways to get the card to fold properly.

One was slicing out the parts that join the pleats together and seeing if that would still keep the shape together. If this one worked then I would have to cut out a band to hold the sides in one piece. I think very fortunately this method failed. If it worked, I would have to do a lot more work for it and it would take too much time.

The second method was a pain and good thing it didn't work either. It was perforating each folding line. THEY'RE ALL FOLDING LINES. What this did was even though it made them fold more easily when you try to collapse the pleats to close it the folds would rip in a way that was very ugly and ruined the look of the box.

Will have to use the final option, which is thinner card that is more flexible. It would be more suitable for folding and strength, I believe, would be fine even though it won't be as strong as that thick card.