
wooden_shield
{
    INPUT: leather, 4
    INPUT: wood_log, 10

    OUTPUT: wooden_shield
}

reinforced_shield
{
    INPUT: copper_bar, 6
    INPUT: wood_log, 12
    INPUT: leather, 4

    OUTPUT: reinforced_shield
}

bronze_shield
{
    INPUT: bronze_bar, 10
    INPUT: leather, 4

    OUTPUT: bronze_shield
}