Traitor/mods/levels/borders.lua

minetest.register_node('levels:border', {
   description = 'Invisible Border',
   inventory_image = 'levels_border.png',
   drawtype = 'allfaces',
   paramtype = 'light',
   pointable = false,
   tiles = {'levels_blank.png'},
   groups = {breakable=1, not_in_creative_inventory=1},
})

minetest.register_node('levels:border_alt', {
   description = 'visible Border',
   drawtype = 'allfaces',
   paramtype = 'light',
   pointable = true,
   tiles = {'levels_border.png'},
   groups = {breakable=1},
   on_construct = function(pos)
      local timer = minetest.get_node_timer(pos)
      timer:start(30)
   end,
   on_timer = function(pos)
      minetest.set_node(pos, {name='levels:border'})
   end
})

minetest.register_chatcommand('border', {
   description = 'Turn invisible borders visible.',
   func = function(name)
      local player = minetest.get_player_by_name(name)
      local pos = vector.round(player:get_pos())
      local pos1 = {x=pos.x+5, y=pos.y+5, z=pos.z+5}
      local pos2 = {x=pos.x-5, y=pos.y-3, z=pos.z-5}
      local node_list = minetest.find_nodes_in_area(pos1, pos2, 'levels:border')
      for _,pos in pairs(node_list) do
         minetest.set_node(pos, {name='levels:border_alt'})
      end
   end
})