This is sketch is just the bones of a DNA double helix without the connecting rods in between. This would be more effective if the two strands were perfectly wrapped around one another. I think it would also work better as a model if the strands were not 2D, that is they had some thickness to them. From here I would curve the helix so that it forms a ring that twists around itself which would be very interesting
This sketch is inspired by a leaf with the veins stemming from a 'backbone'. It would make a very interesting model however may be a bit too busy. This could be easily simplified by removing some of the bottom segments. A way to make this model translate into 3D more effectively would be to make the segments bevelled so that they are higher in the middle and lower where they connect to one another.
Sticking to the natural theme, this sketch also stems from a leaf and is a development of the sketch above. I likes the repetition and pattern that the repeated curves gave so I have translated this into this sketch. To take this into a 3D form I think it would be effective to spherify the design so that it is almost spinning top like.
This is my final sketch and it is actually my favourite. I like the fact that it does not have a start and finish but is actually never ending. It would look better if all the loops were the same size and it was symmetrical however this will be easier to achieve on a computer. I am definitely going to develop this idea further into a 3D model in Solidworks.