Kenko DG Extension Tube Set for Nikon F brand_Fujifilm with a small standard lens:

with a small standard lens: the interior dimensions are approximately 10x14x14cm

You can add your own padding or just use it as it is

This is a genuine Asahi Pentax K mount reversing ring

designed for use with Sony E and FE mount cameras that use Sony's Multi Interface shoe

The Manfrotto 679B is a good quality

Kenko DG Extension Tube Set for Nikon F brand_Fujifilm with a small standard lens:A set of three extension tubes for Nikon F mount: 12mm, 20mm, and 36mm. These tubes have the electronic contacts necessary to maintain autofocus and autoexposure capabilities. If you're curious about dabbling in macro work, this is an inexpensive way to get started.