Second sketch up. I use autocad fusion 360, proE, and draft sight and sketch up is the fastest and most intuitive. Unfortunately it's not very accurate so machine parts with .001" tolerances can't accurately modeled but it works great for architecture, furniture, and layout. Allows you to place fixtures, furniture, and appliances and thenwalk through. It also makes it easy to pivot things such as doors and see obstructions. Sometimes even on machines I do a basic model with sketch up if there are a lot of pivot points and then redraw the parts in cad. It saws tons of time.
By the way, an app is for a phone. What you need is a computer program.