How to use an aerial 36 inches lens

Same material (PVC) but 3 mm thickness, it'll be glued (in fact, welded as the material is melted).

I need 8 very thin (between 4 and 7 mm wide) strips to make the frame, I don't have the bandsaw that would be perfect, so a backsaw is used, but first the cutting is initiated with the trusquin (marking gauge), and continuated with an metal lathe tool, very sharp, and it makes a very satisfying SCRIIITCH noise, the hand must be very well positioned to scratch on the thin strait line made first with the trusquin, then repeated about 10 times on each side, and then, the backsaw to finish. It gives, with the help of  an ébavureur (deburring tool) a very soft edge finish with a little chanfrein (in fact, it's better not to have an angled cut for the upper stripes, the largest ones 7 x 140 mm must have strait edges as they are going to be routed « in between the 7 mm », so lost material isn't a good option).

I really enjoy using the trusquin ! With the sharp tungsten carbide marking tool, it's very pleasant trying to be precise. Even for small woodworks it's smooth, and you can repeat anytime you wish to have a mark on very hard surfaces. Of course, it's better used on the marble than on the wood bench, but it's flat enough for that task.

Very easy to cut with the "milling machine" adapted drill press and an 2 mm tool.

Just a few surgeon blade cuts here and there needed.

Some filling here and there. The soft jaws of my soviet (made in CCCP in the 80's it was just 10 times cheaper than a made in France smaller one) vise are the same 5 mm L shaped profiles used for the frame of the lens, as a very valuable strong material, even if fond on the sidewalk, I don't use it for small projects.

Welding the first 3 x 4 x 130 mm strips with the help of some weights and the appropriate "PVC gel glue" witch is a solvent, that's why welding PVC, if done well (after scratching a little the surface with sand paper) is a good strong bond, just like PMMA with chloroform. A very good ventilation is necessary it's toxic and I also use a little acetone for cleaning. Some glass shelves are used to protect the bench. I don't want to have a sticky woodbench, and glass is very easy to clean with a blade and don't fear nothing except heat, hits and scratches.

Second stage, 3 x 7 x 140 mm strips welding.

Milling with the 2 mm tool.

Aaaargh ! It was doing fine and it slipped, need more new strips to weld.

Nearly a good fit.

Welding the damaged parts.

While waiting for the welding to be strong enough to be machined, trying to polish the front element that's been seriously screeched. Not sure that acrylic polish is enough grainy to make any difference, I need to find the right polishing paste, the cloth is a Tetenal optical polishing cloth, but the paste...

You can read, on the iris lever (yellow part), and in the bright reflection on the right center of the barrel, hand written : "810" (and not "018"), witch is the focal length in millimeters.

One more milling accident, one more strip cut and welded.

Another accident. Last strip, 3 x 3 x 140 mm, on the back, the valet is firmly holding the PVC between two pieces of wood, with old sandpaper on both sides of the plastic to prevent slipping when cutting. In the center, the lathe tool used to scratch.

Last weld.

Velcroed ! and ready for service.

PVC milling is... dirty.

A more inert and solid material is chosen : 10 mm thick PVC.

I really enjoy a lot using the metal trusquin (marking gauge), as mine didn't come with the enlarging lens, I made it with a close-up 52 mm photographic filter and a piece of brass plumbing tube to hold it in place, very convenient ! very precise...

Routing was very fast (with a real table router), cutting the inside frame with the jig saw easy and filling very fast too.

routing with the drill is easy too.

carefully cutting the inside groove, but, there's a problem : clamps are needed to have it flat...

Without clamps, it will never be flat to mont it on the camera : the heat generated by the router has distorted the plastic, merde ! too fast !

After gluing to fix my mistake, it nearly fits the camera frame

A very careful last adjustment is necessary, slow motion here !

very last filling 

the shape is not simple, it's very tiny.

it's perfect.

But it's much too brittle, let's make another one.

I've not been careful enough ! It was nearly over, only half a millimeter,  I turned it on the vise, and it was a bad idea, it broke at first attempt.

It will take time, hand filling is long, but I don't trust my routing skills enough.

Cutting the inside frame with a jigsaw. Very easy with an acrylic blade.

A first attempt at replicating the Sinar board in Betonex type plywood.

Some needles to hold in place before sewing. Nothing really innovative.

The donor for the below has been a leather couch cushion, in very good shape, given to me years ago by a neighbor, it's nearly exactly what was needed.

I had tu unsew it all to do my patron, and with the help of Sabrina, my colleague from the "design vêtement" workshop, made a very square 23 x 23 cm and about 70 cm long below. The front end as already the Velcro tape sewed , it needs a small patch of leather on the other end to finish the tube, and somme Velcro tape too.

A velcro tape (a genuine part, I don't want to meet the Velcro lawyers : 

;o)

is added on the back of the board to hold the below.

The frame is 230 mm square.