Reusable food and drink containers, such a keep cups, are becoming popular. Make sure your containers are clean, washing them in soapy hot water, rinsing and drying thoroughly. Make sure the containers are transported closed so they don’t get recontaminated and take any perishable food home straight away in a cooler bag (with ice brick if a long distance) It is also up to the shop/ cafe if they allow this to be done eg if their scales can be set for different containers.