My Tiger I came with opaque, tan-colored vision blocks. I'm tempted to sueeze a little PVA into the aperture and wait for it to dry into a semi-clear state.

My LHS diesn't have any Krystal clear in stock.

Anybody else got a favorite technique?

Thanks for reading,

Gary

Try using clear nail polish. I have used it on aircraft windows and it seems to work for me.

Cool, thanks for the tip! I'm sure my wife will have some, somewhere.

The problem with putting in a liquid that "dries" is that they all shrink, leaving a sink mark that's near impossibly to flatten out.

If you want to go the translucent liquid route, use 5 minute or 30 minute epoxy. It cures not dries so it doesn't shrink. It can be harder to get a smooth front face, though, so the 30 minute stuff has more time to self level than the 5 minute types.

My preferred method is to cut and insert a piece of translucent plastic (it used to be end pieces of exposed 35mm film, but who has that stuff anymore!) A little fiddly, but guaranteed flat and you can colour the back face of the plastic to simulate the effects of the thicket bullet proof glass.

If making a modern kit with all the fancy coatings, you can buy sheets of plastic in those funky colours you see now and use that.

For installing these piece of plastic I like to use gator glue or PVA as they give you more time to fiddle and get the location right and don't mar the plastic if you want to remove the piece and refit it.

HTH

Paul

Really good advice! I use the 2 - part epoxy glue for light and instrument lenses. The glue sets into a convex shape and is crystal clear, and actually magnifies any instrument markings making them easier to see.

More great advice! Thank you very much. Life would be a lot simpler if they just put the blocks on a sprue of clear plastic.

I don't love clear hyposcopes very much. In my opinion, their visual look on the model is not as evident as on photos of real tanks, and they are delicate. If their surface is curved for bad molding, or other causes, the effect let to desire. I would exclude Kristal Klear at all.
In my opinion, a trasparent piece, to be satisfactory, has to be very flat, and recreate the effect of a double mirror showing the dark inside of the tank, that is very difficuld even with well molded plastic pieces.
A possibility is to insert a piece of clear plastic from inside, but this require the outside being painted before. To improve things, an eventual internal reflecting (or black, considering that it reflects the dark inside) surface inclined of 45° can be added before the insertion of the clear piece (again, a simple rectangle glued with white glue).
I prefer a simpler solution: a sharp, flat and gloss surface applied from the outside, made with a very thin plastic sheet painted with a dark metallic blue-grey on its rear. It has to be glued on the already painted opaque block with a bit of white glue. It is easy to use as a decal and its look is satisfying enough for my eye.