So I can definitely make an 35x35 inch bath box. The inner bath box would be made of 8mm clear plexiglass, the dipper of 5 mm plexiglass. The plexiglas of this size on its own is quite expensive. The inner dimensions would be 992x940x16 mm, so there is enough space on all sides. When you take into consideration the volume of the liquid displaced by the dipper and the plate itself, you will need about 10 to 12 liters of silver nitrate solution. Theoretically I can make the bath box even more narrow, but that would make operating it even more difficult. The outer container would be wooden with the same design as our other bath boxes. It would weigh a lot. The inner bath box with dipper would weigh over 20 Kg, the whole box would weigh over 30 Kg (without the silver nitrate, or the plate itself). So the shipping to Canada would be expensive as well.
So the price for the silver bath box would be 729 USD. The fixer bath box would cost the same amount.
There are really just two ways of shipping. Economy International Shipping (delivery within 2 to 4 weeks) for 150 USD, and Priority International Shipping (delivery within 10 working days) for 280 USD.
If you are interested, please let me know if you agree with the inner dimensions and the price and what type of shipping would you like. I can ship within 5 working days after payment.