Not exactly DIYing, but we have an overflow pantry cupboard specifically so I can buy in bulk when things are on special. It's a bit counterintuitive to spend more money in order to save, but it does work provided you only buy bulk/multiples of core items that you *always* use. For us that's things like favorite tea & coffee, rice, pasta, oats, wine (!), chocolate (!), dunny paper, kitty litter, shampoo, deodorant, etc. A deep freezer lets you buy bulk meat, but that's not something I've gotten organized to do (yet).

Other tip is to always shop during the catalogue period that doesn't have the government pay day in it. The non-gov pay catalogues have more discounts on basic food items, but the gov-pay ones have more specials on processed, value added, discretionary items. Also shopping earlier in the week can get you more specials than on Thur, fri, sat.