1: Make a box, 100mmx100mmx1mm, copy this 3 times and align them together in a row (make sure the 3d snap tool is active and is set to vertex- the 3d snap tool is found on the top toolbar, its icon is a magnet with a 3 beside it. ive made the boxes different colours to differentiate between them.
2: To make the hinge points- Ensure that 3d snap is still active. we are going to place dummy obects at the corners of each box where they will bend together. A dummy object is one tat can be used to manipulate the model, but wont actually show up on renders.
To place the dummy object, click the helpers tab in the create panel, choose dummy and place it on the corners wherethe boxes touch. with 3d snap on they should be created ight on the corners.
3: Now we have to link these dummys to the boxes, and make it as if the four separate boxes act like one piece of card etc. Click th link objects button, then click and drag from the first box to the first dummy. Then from the first dummy to the second box, then the second box to the second dummy etc- basically connect each dummy to the boxes adjacent to it.
4: Now to make the box actually animate. Click auto key near the bottom of the screen. Select the first dummy box, move to frame 20 and right click to insert a keyframe. Move to frame 30 and insert another keyframe. Now rotate the dummy by 90 degrees in the y axis. If linked correctly, this should also rotate the first box about the edge.
5: Select the next dummy, and insert a keyframe at frames 30 and 40. at 40, rotate the second dummy box by 90 degrees. again, if everything is linked correctly it should rotate the boxes as shown:
The reason we include the keyframe at 30 on the second dummy is to ensure that the rotation doesnt start before the rotation on dummy 1 is complete.
6: We will do the same to dummy 3- insert a keyframe at frames 40 and 50, and on 50 rotate dummy 3 by 90 degrees to close the box.
7: To finish, select the box at the bottom of the folded cube, insert keyframes at 50 and 70, and at 70 move the box vertically, as if it hass been picked up.
8: To add the sides of the box, deselect all objects and return to frame 0 on your timeline. create 2 more fresh boxes, snap them to the sides of box 1 and add 2 more dummys to where each should bend.
Now using the names shown above, link box a to the first new dummy, then the dummy to box b. Link box c to the second dummy, and then the second dummy to box b.
9: Now we animate these side panels, similar to before. select box a and insert a keyframe at frames 50 and 60. At frame 60 rotate it 90 degrees in the z axis. do the same for box c. These should combine wth the other parts of the animation, and fold along with the rest of the box before being picked up. heres how the finished animation should look: