You can deduct out of pocket costs for supplies if you donated to a registered tax exempt organization. They should give you a receipt or acknowledgement letter of your gift. (The letter does not have to specific value, you will prove that in other ways.). Gifts to specific individuals are never deductible even if the purpose is charitable.
You can deduct the cost of materials, as well as mileage driving to buy supplies and drop off the finished masks, if you kept records of your mileage. You can't deduct anything for the cost of your time.
These gifts would be a schedule A itemized deduction, if you itemize your other deductions. This gift is not eligible for the special $300 charity gift deduction because to be eligible, such gifts must be money only (cash, check, credit card).
