This interesting four-bar linkage mechanism produces a movement that swishes back and forth in a rather charming way.
Use it to explore the mechanism or as the starting point for your own animated paper character.
Members can download the parts for free at the link, non-members can download the parts for £2.50ukp

Print out the parts onto thin card. I printed them onto coloured card to produce a colourful model.

Score along the dotted and dashed lines, cut out the holes then carefully cut out the parts.

Fold up the base with right angle triangles at the side.

Repeat the process with the box top then fold out the flaps on the hole in the box top and glue them down as shown.

Fold over the tabs on the box end with the circular holes to make triangle shaped tubes. These will strengthen the box as it is assembled.

Glue the box end to the box top. Use the picture to make sure you glue the correct ends together.

Join the remaining box pieces together. Take care to align everything as accurately as possible.

Glue the box sides into place.

Assemble the linkage support as shown.

Glue the linkage support into the box as shown.

Glue together the linkage.

Glue the linkage to the linkage stand.

Assemble the dog-leg bar as shown.

Fold over and glue down the two crank ends to make double thickness card then cut them out.

Roll up and glue down the three pins. Use the arrows and grey areas to line up the ends accurately.

Glue the crank ends to the long arm of the dog-leg bar.

Find the pin with four arrows and thread it into the crank ends. It should turn freely.

Assemble the two crank pieces.

Glue the short ends of the crank to the pin lining them up with each other.

Glue together the handle following the three steps shown above.

Hold the crank assembly into position inside the box and thread the two remaining pins into place gluing them to the inside of the crank.

Glue the end of the linkage to the dog-leg bar.

Glue the handle to the box to complete the model. You can use this as a starting point for your own character or as a demonstration of how four bar linkages can work.

I used mine as an animation to go on the end of my forthcoming YouTube videos. You can see an animation of it in action here.

I’ve also tried creating my own character that uses this mechanism. Look out for a finished version in a download shortly!