Based on this pattern, I've made a heat therapy pack for my Mum, using denim and fabric scraps to make the cover, which closes with velcro. Inside I have used calico material for the lavender and wheat pillow. All fabric used, including calico, is from my op shop stash. I used thrifted lace and a recycled birthday card to write a message.
Heat packs are microwaved for approximately 2 minutes, they small divine and feel great on the back of shoulders.
Unfortunately, what I probably should have considered, is sending such a weight to the UK; $40! Ouch.