A plant for manufacturing a continuous latex foam layer (2) to form mattresses (6) provided with cells (5). The plant comprises a plurality of laying planes (7) provided with a plurality of separate tables (13) separately arranged side by side to form a surface for the foam deposit.Each table comprises protuberances (14) and the arrangement of the protuberances on a table can differ from that of the juxtaposed tables in order to create supporting areas for the different body parts of the user.Preferably the tables (13) with their protuberances (14) are slidably fitted onto the laying planes (7) and can be easily and quickly replaced with separately provided tables having protuberances (14) differently arranged in order to meet the support capacity values required by different users.