Collect a long plastic bottle and cut off the bottom. Secure it to the plant when the cucumber is small enough to get it through the neck of the bottle (if not, you may have to cut the neck off). Try and place something underneath the bottle so it doesn't weigh the plant down.
Small Allotment Pond Idea
This is an idea we got from a fellow allotment keeper. Get an old bucket, bigger the better. add some gravel, a brick and an oxygen giving plant. Fill with water and some frog spawn and you have a great place for frogs who will eat some garden pests.
Slug Trap
Get an old plastic bottle, cut in half, fill the bottom with a little beer. Place the top back on upside down and burry in the ground. Place an old plastic plant pot over the top with holes cut around it with enough space for slugs to get in and there you have it, an easy and cheap slug trap.
Self watering plant pot and cloche idea.
For the self watering system, cut a plastic bottle in half, add some water to the bottom half. Lay some cotton wool at the neck end and pull some through, long enough to reach the bottom of the water. Add compost on top of the cotton wool and put it back into the bottom half (as shown in the picture). To make a cloche top, cut the bottom off another plastic bottle and place on the top.