I found this a while ago at Ryton Organic Gardens. Something about it really appeals to me, and it has substantially influenced my 3D project (as you will see later). My art tutor was telling me how these pods hold fleshy seeds inside them, and when they fall the pod structure is strong enough to prevent the seeds from rotting on the ground. What a clever design.
This is a lovely drawing – looking forward to your 3D project. What is it? Looks like a physalis or similar.
I think it is Physalis, or Chinese Lantern. There is an amazing picture of it here – http://www.flickr.com/groups/greatpix/discuss/103336/