How to print some Lego accessories with a 3D printer?

At present, FDM's cheap 3D printer can print Lego bricks. But the accuracy is not good, there are many burrs, and the printer itself has many pits. It would be unwise to put the printer in Lego (mainly for playing with 3D printers, of course, that's another matter). If into the pit Science and Technology, remember that among the parts, shafts, pins, gears and other parts related to transmission are imported genuine Legos, and other building blocks are made in China. 3D printing is the only choice for special-shaped parts that do not exist in Lego. However, you can actually entrust others to print for you.