Over at Instructables, user Banjomaster shows how to make a fisheye lens for his Nikon D90 for just $16, with the help of one of those wide-angle doorway peephole lenses. The image associated with this post is best viewed using a browser. It looks like a pretty simple mod, both in materials required and construction method: It only needs a couple pieces of particle board, the aforementioned peephole lens, the spare lens shield that came with his camera, and of course some duct tape. The only possible caveat: The replacement wide-angle lens is significantly smaller than the camera’s lens, so there’s a circle around all of the shots. On the other hand, it’s sort of cool; it makes everything look like you shot it through a hotel door.

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How to: Make a Fisheye DSLR Lens for $16 [DIY]