Turtles are very timid animals , they wont make nests until u give them what they need , you need to put in some twigs and some straw , hay type stuff because of there feet they cant use anything too...
If you don't know....
You don't "build a nest" persay... you get a nesting box. You install the nesting box in the far corner of the cage (safer there) and let the parrots work their magic. You can...