I've created different products over the years, from digital tools to reflective tweedbuttons (handmade/real stuff :)
PolarWhite stationery is a MockUp collection for Photoshop CS6 and up.
I needed a presentation tool for my designs, and created a versatile mockup package that are useful for most design projects.
Sampled Light is a HDRi sky sequence loop (!) ready to use. This will give you a unique way of presenting your 3D renders.
You can buy it at Creative Marked.