Just kidding! They are as difficult to make as you want them to be. It depends on your level of skill with tools and your creativity! Cost can be a big factor too. There are a lot of different materials, so acquiring them takes time. There are different sets of plans available on the web. The most popular set is the one put out by Dalek Builder's Guild. It's a bit long and and also a bit short on dimensions, but there are builder's groups on the web as well.