Once a print job is done, there are multiple ways to finish it, particularly depending on the type of printing used.
Filament Printing - if supports were used during the printing process then they will have to be snapped off or cut off with snips. It is rare but possible that you can melt the supports off if they were printed in another material. ABS will melt with acetone, HIPS will melt with limonene and PVA will melt with water. Rafts will also need to be removed, they are made to easily peel off but if that isn't the case, pliers or snips will help.
SLA Printing (not available) - printers like the Form or LittleRP print with liquid resin. Prints that come off of these can be strengthened by placing them outside in the sunlight or under a UV light, otherwise they will retain a little bit of flexibility. The prints may also need support removal as well.
Powder Printing - prints made with gypsum powder need to be brushed, cleaned with pressurized air and then finished with superglue (3D System's works best), wax or epoxy