I found time this week to knock up a first prototype for the internal encasement. This I made using a cheap and nasty closed-cell foam sleeping mat costing €2.50 from the local D.I.Y store. The first change I made to the design was to dispense with the Duct Tape used in the first example. Duct Tape weighs around 0.15g/cm (I can hardly believe I just typed those words. Looking at it written down it sounds like one of those thoughts that should better be left unsaid!). For the construction I first put to paper this would ammount to 30g of tape to hold 30g of foam together. Seeing an opportunity to halve the weight of the inner I experimented with glue. I know from past experience (don't ask) that anaerobic Cyanoacrylate (super glue to you and I) works well with foam matting. after a little fooling around I found a way of making neat mitred corners by scoring two shallow lines with a sharp craft knife, peeling out the strip of foam between the lines, squeezing a glue line into the groove and folding to form the corner:
With three such joints and a butt-joint the construction of a rectangular cross section tube was soon realised:
Three mitred joints and one butt joint make the basic shape of the inner.
One end was then closed off by butting a rectangle against it and placing a smaller, tight fitting rectangle on the inside face of the base to create a double thickness.
The base was butted against the tube and a second layer added on the inside face.
Since I want a top-loader I had then to create some internal structure to support the camera body leaving the lens suspended in the bag. I made two, double layer verticals, beefing up the top edge by wrapping one layer around the other (the picture does the job better than this description honestly):
Supports with a "beefed-up" top edge were made as shown above. The example shown would be glued to the side wall of the tube. The other would be free standing and consequently the spacer layer was extended to the full length of the first to provide greater stiffness.
The verticals were then glued into place in the box. They act as supports and create two separate compartments:
Image showing the two vertical supports glued into place.
I then constructed a tight fitting hinged lid and the resulting encasement ended up as shown in the next image:
The completed closed-cell foam encasement.
On balance I'm pleased with the result. The integrity of the joints is good. The construction feels robust enough for its purpose (it will not carry any load, that's left to the bag and webbing), it's cheap and the whole thing weighs just 30g. Most importantly I can put one together in half an hour. That means I can make several for different gear selections and can tinker with the designs until I find what works best. This first example almost certainly won't be the final design. With my E400, 14-42mm lens, 25mm fixed focus pancake lens and a couple of filters and media cards there's a lot of space over. I'm also not convinced that the lid, in its current form, will work in combination with a roll-top dry bag. I think it may get in the way when trying to access the camera through the open top of the dry bag.
Still, the most efficient way to improve the design will be to live with this one until I've identified all the glitches. Before I can do that I need to source a suitable dry bag and devise the strapping. When I next make any progress, you'll be the first to know.