Threed

Very impressive One Pager that renders your uploaded design within a mobile device, allowing multiple 3D angles and colors. Make sure you read their About section explaining their vision for in-browser live-rendering.

FYI: if you need an array of device screenshots, One Page Love offers a $10 service called Screenshot Concierge.

This website has unfortunately been redesigned or gone offline, so I have removed the direct link to it. The screenshot below hopefully preserved enough of the design but if you are really keen to inspect further, try this Archive.org link. FYI: the site was first featured on 28 November 2017.