I found a useful method to attach the pvc pipes to the wood. In the UK hey are called 'spring toggles'
http://www.screwfix.com/p/rawlplug-spring-toggle-m5-x-80mm-pack-of-20/98223?cm_mmc=GoogleBase-_-Datafeed-_-Screws%20Nails%20and%20Fixings-_-Rawlplug%20Spring%20Toggle%20M5%20x%2080mm%20Pack%20of%2020
It is hard to explain what to do but really quite intuitive when you see the screws:
1. Firstly drill matching holes in the wood and the pvc and then remove the pipe.
Then make the hole in the pvc larger in diameter than the hole in the wood.
At this point assemble the rest of the frame (everything but the rail).
2. Push the screw up through the wood to the surface where the pvc is going to sit, and use a washer.
3. Attach the toggle to the top of the screw.
(do step 2 and 3 for each point where you are attaching the pipe)
4. Then line up the pvc and push the pipe onto the toggles, the toggles will snap out when they are through the pvc.
5. Finally tighten the screws so that they lock down the pvc to the wood.
There is an example of how they work here about halfway down the page under the heading 'Spring metal toggle fixing':
http://www.diydata.com/materials/wallfix/wallfix10.gif
http://www.screwfix.com/p/rawlplug-spring-toggle-m5-x-80mm-pack-of-20/98223?cm_mmc=GoogleBase-_-Datafeed-_-Screws%20Nails%20and%20Fixings-_-Rawlplug%20Spring%20Toggle%20M5%20x%2080mm%20Pack%20of%2020
It is hard to explain what to do but really quite intuitive when you see the screws:
1. Firstly drill matching holes in the wood and the pvc and then remove the pipe.
Then make the hole in the pvc larger in diameter than the hole in the wood.
At this point assemble the rest of the frame (everything but the rail).
2. Push the screw up through the wood to the surface where the pvc is going to sit, and use a washer.
3. Attach the toggle to the top of the screw.
(do step 2 and 3 for each point where you are attaching the pipe)
4. Then line up the pvc and push the pipe onto the toggles, the toggles will snap out when they are through the pvc.
5. Finally tighten the screws so that they lock down the pvc to the wood.
There is an example of how they work here about halfway down the page under the heading 'Spring metal toggle fixing':
http://www.diydata.com/materials/wallfix/wallfix10.gif
