UnderPressur

My son and I tried to make homemade sodium acetate with baking soda and vinegar and filtering with carbon..no luck! His project is due in 2 days and NO ONE sells sodium acetate at stores anymore! I am stuck..i want to try the homemade version again...can any one help? This is for making hot ice but we already used the Instructables version...or is there something else I can substitute ???:doh::doh::doh::doh::doh: