You do not have time to protect your tools from scratches, falls, or other damage. You need to have equipment at hand that can be used at all times.
Get tools made of more durable materials, or use protective covers or cases. Choose something that can bear intense everyday use, still lasting even years later. The possibility of easy swapping and cheap replenishment of writing media will certainly come in handy.
KOH-I-NOOR HARDTMUTH TIP: Thanks to their metal body, the Versatil mechanical pencils protect the lead inside. However, it also works when broken lead and it can be easily supplemented or exchanged.