Kerry Wong built this DIY dummy load in a hard drive cooler aluminum case:
Basic constant current dummy load using an Op Amp and a by-passing MOSFET is very easy to build and had been made quite popular following Dave’s video on EEVBlog. I happened to have an old aluminum hard disk cooler case collecting dust. The die-cast aluminum case is relatively thick, making it an excellent heat sink. So I thought why not use it to build a dummy load myself?