Thought I'd broach the discussion of what, exactly, it would take to get an amateur rocket to orbit. Obviously I'm not suggesting that anyone attempt to build an orbital rocket in their backyard. This is more a design question -- what would be the simplest, cheapest, most dependable option for getting a rocket into orbit at an amateur level? Things to consider include: Staging: Serial or parallel? Fuel: Liquid, hybrid, or solid? Guidance: Gimbal, differential thrust