Fillets can be generated as follows:

Standard functions:

• cube_fillet_inside (generates internal fillets based on cube dimensions)
• cube_fillet_outside (generates external fillets based on cube dimensions)
• cylinder_fillet_inside (generates internal fillets based on cylinder radius)
• cylinder_fillet_outside (generates external fillets based on cylinder radius)

Internal functions: (not normally modified, but can be modified to change fillet shape etc.)

• linear_fillet (straight edges)
• corner_fillet (90 degree corners)
• ring_fillet (cylinders - inside and outside)
• profile (generates the 2d profile used to set the fillet shape)

There are more advanced fillet libraries and functions available, however, sometimes you just need a basic fillet with a low computational overhead that can be applied quickly and easily to selected objects :)

###PS: You can help support my designs by downloading and liking here: https://www.prusaprinters.org/prints/96739-simple-fillets-library###