An automatic plant for preparing paints and the like, comprising - an automated stock configured to contain a plurality of closed containers (C', C") pre-filled with a neutral base, wherein the automated stock has at least two storage sections (28, 30) configured for receiving containers (C', C") with different sizes, wherein the automated stock includes an automatic pick-up device configured for picking up the containers (C', C") in said storage sections (28, 30), - an automatic process line comprising: an inlet and dimension verification station, a drilling station for the formation of holes in the lids of the containers (C', C"), a dosing station for dosing dyes through the holes of the container lids, at least one stirring station for stirring the containers (C', C"), a labeling station and an outlet station, - a robotic unit movable between the various stations of the automatic process line to pick up each container (C', C") in the inlet station and transfer it in succession from each station to the next station until the outlet station, said robotic unit having an adjustable gripping member configured for gripping containers (C', C") with at least two different sizes, wherein said robotic unit carries a cap application assembly configured to apply caps for closing the holes formed in the lids of the containers, and - a control unit configured to receive paint orders including information relating to the size of the containers and the color of the paint requested by the buyer, wherein the control unit following the receipt of an order, controls the automatic pick-up device for picking up from the stock successive pre-filled containers with the sizes corresponding to the input order and controls the robotic unit to adapt the pick-up device to the size of container which from time to time are placed in the inlet station. - an automated stock configured to contain a plurality of closed containers (C', C") pre-filled with a neutral base, wherein the automated stock has at least two storage sections (28, 30) configured for receiving containers (C', C") with different sizes, wherein the automated stock includes an automatic pick-up device configured for picking up the containers (C', C") in said storage sections (28, 30), - an automatic process line comprising: an inlet and dimension verification station, a drilling station for the formation of holes in the lids of the containers (C', C"), a dosing station for dosing dyes through the holes of the container lids, at least one stirring station for stirring the containers (C', C"), a labeling station and an outlet station, - a robotic unit movable between the various stations of the automatic process line to pick up each container (C', C") in the inlet station and transfer it in succession from each station to the next station until the outlet station, said robotic unit having an adjustable gripping member configured for gripping containers (C', C") with at least two different sizes, wherein said robotic unit carries a cap application assembly configured to apply caps for closing the holes formed in the lids of the containers, and - a control unit configured to receive paint orders including information relating to the size of the containers and the color of the paint requested by the buyer, wherein the control unit following the receipt of an order, controls the automatic pick-up device for picking up from the stock successive pre-filled containers with the sizes corresponding to the input order and controls the robotic unit to adapt the pick-up device to the size of container which from time to time are placed in the inlet station.