blockgame/mods/bg_player/hand.lua

local function create_group_cap (max_level)
	return {maxlevel = max_level, times={[1] = 1, [2] = 2, [3] = 3}}
end

minetest.register_item(":", {
	["type"] = "none",
	inventory_image = "[combine:1x1",
	tool_capabilities = {
		groupcaps ={
			uses = 0,
			cracky = create_group_cap(3),
			stoney = create_group_cap(3),
			dirty = create_group_cap(3),
			woody = create_group_cap(3),
			planty = create_group_cap(3),
		},
	},
	node_placement_prediction = "",
	range = 5.8,
})