Auttakaa

Materials:
Rubbish marketing marbles in a net, disposable plastic cup (hoop), drawing pins, paperclip

Does it work:
Yeah, there's not a lot to go wrong with this. This is the one that started it all. It was all downhill from here.

Hardest bits:
Staying awake at work for long enough to dream up the idea of making stuff.

How long to make:
Minutes.

Special bits
The marbles are from a crude marketing campaign. They don't bounce, and if you drop one onto the desk it makes an amazingly loud noise. This is a game of office Russian Roulette. You can't miss, or you have to come up with a good excuse for the sudden clanging noise.

Balista

Materials:
Paperclips (body, trigger), elastic band, tie-wraps (legs), pen refill (bolt)

Does it work:
Yep. In fact, it's surprisingly accurate and can hit a plastic cup from a meter or so away.

Hardest bits:
Attaching two paperclips together stiffly enough to stand the strain of holding the elastic band back.

How long to make:
A few days, on and off.

Special bits
It's got a working trigger mechanism at the back. You squeeze a hinged paper clip and it forces the elastic over the catch, firing the bolt.

Plane

Materials:
Paper, paperclips, elastic band, plastic disposable cup (propeller)

Does it work:
More or less. The prop spins and blows air around, but it doesn't really make enough thrust to fly further than a good throw will take it.

Hardest bits:
Making a thrust bearing for the prop to spin on. This bit removes lots of the energy from the band. The prop was quite hard too.

How long to make:
Just an afternoon. It's dead simple really.

Special bits
It's got undercarriage, which not many paper planes have.

Catapault

Materials:
Paperclips, elastic band, lead pencil.

Does it work:
Kinda. It's a bit crap really though.

Hardest bits:
Getting it to fire straight. It'll chuck the bit of pencil a few meters, but in a random direction.

How long to make:
Barely an hour or so. Dead simple.

Special bits
None really. In fact, it's quite shit.

Wind up car

Materials:
Paperclips, pull back motor.

Does it work:
Hell yeah! The original model car was found in the drawer of someone who had left. It was vastly overweight, being die-cast, so I put it on a diet. Now it can do donuts. Yay!

Hardest bits:
Fixing the front bits to the motor.

How long to make:
Maybe a day. The axle holes are time consuming and I got them wrong a lot.

Special bits
It's got grippy elastic band tyres, but it can still wheelspin all its power away on the spot.

Ratkaisu kaikkiin ongelmiisi!