Can someone with a constructed box please tell me what depth the wooden panes on their box are please? I am looking for a comparison to work out what the depth is on the Hudolin, it looks to me to be about a quarter inch, which may cause some strength issues...

I am working on Windows this week I will try to detail step by step how I did my windows. Maybe that would help?

It's not the building of them I am trying to work out... it's how deep they are on the Hudolin.... how far the glass sits back, from the pics I have they look to be quite shallow.

Actually looking at Crispin's build those are also shallow...

So I hope they are not less than a quarter inch, proves it can be done that thin

The glazing bars on my box are less than 1/4" deep and were overlapped by cutting 1/8" deep slots at the cross points - quite fragile relatively speaking, though I've never had any break, even while chiselling off the old plastic panes I used before the renovation. The panes are so small that the thin bars are not too vulnerable. The panes are glued on the back with clear sealant applied with a caulking gun. I'd originally planned to back them with another set of glazing bars on the inside to improve the look, but I've yet to get around to it.
If security is an issue you could back the set of panes with a single 1/4" to 3/8" thick acrylic sheet, which would be virtually indestructible.

Crispin

Security isn't the issue, more me accidentally breaking them while moving things

I am wanting to put a set on the the inside so that they mirror the the outside as my doors will look the same inside as out mostly becvause I loke how it looks but also because it will make setting the lock easier if the door is thicker.

I am figuring on 3/4 inch in width for them so they should be ok that way, was just worried about them flexing and breaking in the other direction.
I also have the issue that the total space (depth wise) for the windows in the doors is just 1/2, basically the thickness of the plywood if I am to trim out the inside.  The walls will not have this issue as I will be leaving them flush.