I had a look at the kickstarter for the olo printer that you mentioned, the resolution limit IS the screen res. of the phone, the size limit IS the screen size of the phone, they mention a future project for a tablet that might be similar, and the big issue against IS the 'white light" curing resin(will need a more sensitive resin due to the lower energy in 'white light' vs near UV that the peachy uses) and the fixed (and small) build volume, and the smart phone MUST be in airline mode while printing, so if you want to USE the phone while printing, then you will NEED a second phone so that you have one to use and one to print with so that really adds the price of a second phone(with a very high res screen so that you can get the small details that you are likely to want on the small prints) to the price of th kickstarter, and the NEED for special white light resins which are not so common