I know that a lot of people already do this, but over the last few years I have had a lot of fun (and satisfaction) using leftover resin sprues for basing!
They come in all shapes and sizes, and since almost everything I have to work on these days is resin, why not get some use out of all that? I think these sprues are from 4-5 different manufacturers...
While you can do something very similar with sculpey, the resin pieces are super strong. I used them to support some Reaver jetbikes in my Dark Eldar army, as well as on some of my 40k terrain.
It does not take a lot of extra work to get the sprues in a condition for basing. I included some of this in the 'Blasted Concrete' video, since I am sure a lot of you have (or had) this stuff sitting around.
Once it's all painted up, it looks quite nifty!!