This script creates public synonyms for all TABLES/VIEWS/SEQUENCES owned by a user. This script can be run by any user to create public synonyms for any other user as long as it has CREATE PUBLIC SYNONYM privilege.

set verify off
set pause off
set doc off
set heading off

accept s_user prompt 'Enter object OWNER to create synonyms FOR : '
prompt
show user
prompt 'Creating PUBLIC synonyms for TABLES/VIEWS/SEQUENCES owned by &s_user'
prompt

DECLARE
 sql_stmt varchar2(1024);

cursor get_tab is
    select table_name,owner from all_tables 
    where owner = UPPER('&s_user')
    and table_name not in (select synonym_name
                           from all_synonyms
                           where owner='PUBLIC'); 

cursor get_view is
    select view_name,owner from all_views
    where owner=upper('&s_user')
    and view_name not in (select synonym_name
                           from all_synonyms
                           where owner='PUBLIC');

cursor get_seq is
    select sequence_name,sequence_owner from all_sequences
    where sequence_owner=upper('&s_user')
    and sequence_name not in (select synonym_name
                           from all_synonyms
                           where owner='PUBLIC');

BEGIN

/* Tables first */

FOR tab_rec in get_tab LOOP

   sql_stmt := 'create public synonym '||tab_rec.table_name||' for '||tab_rec.owner||'.'||tab_rec.table_name;

   EXECUTE IMMEDIATE sql_stmt;

END LOOP;

/* Views */

FOR view_rec in get_view LOOP

   sql_stmt := 'create public synonym '||view_rec.view_name||' for '||view_rec.owner||'.'||view_rec.view_name;

   EXECUTE IMMEDIATE sql_stmt;

END LOOP;

/* Sequences */

FOR seq_rec in get_seq LOOP

   sql_stmt := 'create public synonym '||seq_rec.sequence_name||' for '||seq_rec.sequence_owner||'.'||seq_rec.sequence_name;

   EXECUTE IMMEDIATE sql_stmt;

END LOOP;

END;
/