I've had a few days of experimenting with lots of different ideas.

(That and taking #1 daughter to university interviews! She's hoping to study graphic design so we're carrying her huge portfolio case all round the country.)

One of the things I have been trying to do is recreate a sort of slow motion movement as demonstrated by astronauts on the moon. I have only a vague idea at the moment but I think I'd like to produce a model with an astronaut jumping up and down (slowly) next to a lunar module.

I thought I could fit a long pendulum into a box. Realistically, 17-18cm is the max length feasible.

After a quick calculation I reckon the period for a pendulum of that length should be just over 0.8 seconds. Just about right.

To utilise the movement I'll need a long arm sticking out sideways from the pendulum, the longer the arm, the greater the range of movement. The problem being that this means that the box with the model in will need to be both tall and wide. Tall for the pendulum, wide for the link arm.

To fit everything into a narrower box I'll have to wrap the mechanism up a bit. I reckon it should be possible using a bell crank. Although this should make the whole mechanism much more compact  I foresee a possible problem. There are now three joints which weren't there before, each of which will add a little friction to the movement. Perhaps if I use paper hinges rather than the usual card? More experimentation I reckon.