Lowepro Mini Trekker brand_Photographer's Formulary securely so long as you

securely so long as you don't turtle

and the Reverse Attachment

This one has a decent amount of cosmetic wear and is missing a section of leatherette around the top of the viewing lens (see photo)

This SLR Magic Variable ND Filter Mark II is specially designed to minimize the weird uneven vignetting that sometimes afflicts variable filters

5L of working chemistry

Lowepro Mini Trekker brand_Photographer's Formulary securely so long as youThe Lowepro Mini Trekker isn't that mini: it's big enough to hold a reasonably sized camera setup. About the size of a "normal" school backpack, it features a padded compartment with dividers, a couple of front pockets, and provision to attach a tripod. Interior dimensions are approximately 12x30x36cm.