You have to buy a blueprint for that particular tank. After doing so, click the crafting table and select the parts you want.

Crafting materials come from recycled parts, which you can pick up in the yard. (Don't forget to recycle them.)

what i meant is craft all missing parts in one go like the buy missing parts in the tablet

When you click on "buy missing parts" and it brings up that small window with the Accept and Cancel buttons, take a note of those two sliders above. One is orange and says "Painted". To the right it says "Buy parts" and is black. Move that slider to the right.