As long as you are in this hobby, you will be buying tools.
Sanding blocks are a must. I like the T-Bar sanders from Great Planes. I have 3, each with a different grit. You are way ahead of the game with the Dremel tool. You will need a covering iron and heat gun. The list is endless.
I use one of the building boards from Great Planes.
As long as you are in this hobby, you will be buying tools. I know I said that already but its an absolute fact.