We used the plans downloaded from this website and they worked great! Our whale has been a lot of fun for the whole congregation and created a great deal of interest in Children's ministry. We are even having a contest to name it.
Warning about using your Whale outside:
One bit of advice. We had our whale outside so everyone in the church would have to walk right past it. This was fine until our whale overheated. The duct tape stickum got soft and we split a seam. It was no problem to fix, but a word of warning for those who might expose their whales to prolonged direct sunlight.