This are my flash modifiers.
Started with the Pop-up flash bouncer that I got a template at diyphotography.net . Covered the inside with aluminum foil. It's foldable but the cardboard I had was on the thick side. If I do another one it will be with thinner cardboard.
Then the pop-up flash diffuser. Made it from a plastic notebook cover with a layer of wrapping PE sheet and tuned to almost perfect fit on the D5300. Take time to tune yours. I might have started with some template that I don't remember anymore.
top left: Pop-up flash bouncer, top right: Pop-up flash diffuser, bottom left: Flashbender clone, bottom right: Double sided flag
For the Flashbender clone I've used black and white sheets of EVA foam glued together, a piece of Velcro, wires and gaffer tape. Dimensions are approximately 275mm wide by 240mm tall plus about 35mm for the attaching band (black part is a 275mm square and white part a 270x235mm rectangle). Under the gaffer tape, the 3 "wires" that make the adjustable structure were made by braiding 3 24AWG wires (isolated solid core copper) that I had on my electronic projects leftovers box. I found the braids too soft so I've decided to use 2 braids on each "wire". It ended up a little too stiff, being a little harder to bend to the desired shape, but it holds that shape nicely and will last longer, as the risk of breaking the wires after multiple bends is lower. It fits nicely on my Samsonite Medium No Shok Foto Photo Shoulderbag and adjusts perfectly to the Nissin i40.
The central part of the adjusting band, that it's not cut, must match your flashgun width. The adjusting wires must all end at that area to provide enough support for the whole thing.
The double sided flags are just two white foamcore (or paper-faced foam board or k-line) rectangles with black card stock glued on the one side and a Velcro band on each side (I had matching colours but it obviously makes no difference at all).
Flashbender back side and pop-up flash bouncer
Finally the snoot and grids. The snoot is a simple black EVA foam rectangle with some gaffer tape, made to fit my Nissin i40. The grids, made in several lengths to test it later (didn't have patient and/or need to do it), are just 8mm black straws glued with hot melt glue, a bit of tape to help during the construction, and covered with black EVA foam making a tube that enables combining them with each other (increasing length to taste) or with the snoot. This construction follows the widely spread form and construction materials and method, just tweaked to my taste and flashgun dimensions.
The velcroed band, Honl speed strap style, isn't quite ok to me, mainly because the lack of elasticity of the neoprene piece I had (a leftover) and because I haven't cut the Velcro band. I think I'll redo this one soon.
Grids and snoot and a Velcroed band