Cheers Tony, glad you're enjoying it

Sure thing, the plywood is 18mm 'structural ply'. One sheet just about did the two side panels, the front, back and the top bit at the back.
I've made the bottom out of moisture resistant MDF although my first attempt was about an inch too small at the top and bottom for some reason! Measure twice, cut once and all that

Luckily there was more than enough left out of a sheet to make another one.
The corners are mitred at 45 degrees which isn't the same as the mitre-lock joints the original cabinets come out of the factory with. I am hoping pinning, gluing and running a bracing piece with the big leg bolt plates on the inside will be enough structurally but time will tell.
As I said this is more an experiment/challenge to see if I can do it. Worst case I'll have to shell out £500 for a new cabinet from Manny but nothing ventured, noting gained and all that!

The hardest parts were countersinking the button holes, routering the glass channel track in the sides and mitering the corners, the rest was pretty easy really.
I'm no expert but if you need any more info let me know!