Now swimming pools come in all shapes and sizes so first you have to decide on the shape you want, ie rectangular ones make great pools for actually swimming in for exercise, but do look a bit boring, also you need to decide how to pump the water into the pool so it overflows into the resevoir, maybe a water feature or maybe a jaccuzzi type thing.
Anyway the first thing you need is one of these.
Now this one costs 2,500baht per day, you will also probably need a 10 wheel truck to get rid of excess soil, now this digger was the one we used for the initial digging for this pool, we then had to get a beasty makro in to finish the job as this one didnt have the reach, yep we went down 3 and a half meters for this pool.