Your probably out of luck for a kit of a water slide. I did find this though it's a Water Flume (log ride on water).
http://www.vernonriley.com/faller_pirates.htm
Faller is probably your best shot at any kind of amusement park attraction. They make quite a few different models in that area. A water park wouldn't be to hard to do from scratch if you have photos of one.
Scratch building one..
Human figure is about 2.5 => 3 feet wide. Water slide are about 3x that in diameter so about 9 feet wide at the outside. That is about 1.2 inches in diameter. If you found some flexible rubber tubing all you would need do is cut that in half and add the pylons to hang the slide with. They could be made from wood doweling or other such material.
Note: For safety it would be good to make a small jig or clamp to cut the tubing with. Tubing can roll or slide out of position if your putting pressure on it with a knife. If you are holding on to the tubing with your fingers this could have unfortunate results. So I would clamp it down and cut. This will make a cleaner more accurate cut as well.
Finding plans
Do a google map search for Water Parks (as they are called in North America) and you will find dozens. If you use Google Earth you will be able to measure the plot of the park or slide. Then layout the slide much like a string (with the tubing) add the pylons and paint. The larger slides and pools are pretty simple to make.
You can also look for Water/Amusement park maps. These are maps used for people to make it through the park. They can be quite accurate and have good illustrations of the rides within. So it's a good place to find drawings of a ride you would like to model.
Figures for the Slide/Park
One thing you will need is people (lots of figures) to make it look like it's a popular place. Which is probably why you don't see a scale model of one. As it's the figures that will make it come to life. They could be hard to find in variety and quantity to not have to many repeated. If you are painting your own could take a bit of time too. Remember your looking for beach figures mostly as they would be in swim wear while at the water park.
Painting and Finishing
- Recovery/Splash down pools
Water can be added as water is modeled many times and there are many articles on creating water for Model railroad scenery everywhere.
- Water slide itself.
To make the slide itself look wet.. I would paint the entire slide with a flat color (blue is most common). Outdoor slides are very much subjected to the rays of the sun beating on them and they become dull after a time. You can use this to your advantage. Then run a bead of gloss paint down the center of the interior of the slide to simulate water.
So to scratch build one..
- Map or aerial view of park
- Launch Tower (you can find staired HO towers that can fit the bill or build one from detail parts (Grandt Line Products/Micro Mark/Tichy)
- Rubber tubing (make note of what material the tubing is made of so you select a paint that will work with it.
- Doweling for the pylons of various dimensions. To hang the slide
- Splash down pool (not to deep about 2-3 scale feet deep) as kids are short.
- Paint (both flat and gloss) blue is most common (Pylons are usually Orange or White to bring contrast - as you want people to identify it's a water slide and not another amusement ride)
- Figures lots of them (water parks are usually quite crowded - so be prepared to add 50+ figures to yours if open for the season).
Hope that was helpful.
Ron