The giraffe project is in need of a retractable head.
I need to be able to extend or retract the giraffe neck and for it stay in place. I had used a similar mechanism in the boxer projects to keep them in position but fancied that it could be made slmpler.

I’ve come up with this single part which doubles as an outer sleeve and a leaf spring combined into one piece.

The secret is this extra millimeter. Once the parts are folded round and glued together they make a small curve of card which acts as a spring.

If you are a member you can download the parts sheet and try it out. There are only two parts but it works remarkably well.

Fold up and glue the out tube as shown.

Give the spring part a gentle curve, fold up the valley folds then glue the tabs back on themselves onto the end of the tube. The spring is curved along the dotted lines.

Inside view showing the spring in place.

The inner tube is one millimeter smaller than the outer tube. It slides into place inside the outer tube and is free to move back and forth. The spring keeps it in position. The finished result will translate nicely into the giraffe project allowing the head to be pulled up and down and holding it into position.

It occurred to me that a modified version of the slider tube would work well holding an elbow type joint into position. The extendable slider tube would work in the same way as a muscle.

This is a smaller version of the slider tube in the download fitted into an elbow. It needs a little work but could be an interesting project!