I saw one of these years ago made in wood.

The handle follows an elliptical path whilst the blocks move in linear slots.

Stangely comforting to use.

1. Print 2 blocks, 1 bar, one handle and base.

2. Tidy up the holes in the bar.

3. Insert one block into each slot.

4. Use washers and self tappers to attach the bar to the blocks.

5. Attach the handle, again with self tapper and washer.

Hint. Don't overtoghten the screws, there should be free movement of the parts.