Level 122
prefix the column names with the table name, using a period
$Query = DB::tables('melanine_finishes','melamine_out_finishes', 'plastic_out_finishes',)
->select('melanine_finishes.item_no', 'melanine_finishes.id', DB::raw('SUM(qty) AS qty'),)
->groupBy('item_no', 'id')
->orderBy('created_at','desc')->paginate(5);
for example (I don't know which of your tables has item_no). Repeat for all fields
Also, rather than just list the tables, I would recommend explicit joins - or better, use Eloquent.