So far so good Georgio.
In fact your drawing looks almost identical to one camera that I have in my cupboard and also in many 'ready made for sale' pinhole cameras offered for sale.
It would be interesting to see how you get on and don't forget to show us all some resulting pictures when you take them.
As this is your first posting, I'm unsure what your skills are, but if you are a beginner, may I suggest that you look up Harman Reversal Paper, whose use is ideal for pinhole work, giving you a positive print straight away, so saving you doing negatives and then positives.
I have now attached a link below, which says that the manufacturer is out of stock, but I am sure another seller will have some for sale:
https://www.ilfordphoto.com/harman-direct-positive-paper-sheets
Good luck!
Terry S