rivet lock

hi I am a first year student lower technical education and this is my this is my school project ( hidden / secret locks.) the assignment was as follows design with freecad a lock that consists a max of 7 parts
A - the lock may not be easily seen or directly be noticed.
B - must have a simple construction.
C - for which purpose the lock should serve.
This lock is specially designed for the use of secret compartments in furniture and doors of hidden passages.

I have received for this school project a B +
and i was wondering if anyone has ideas to improve this lock for a better note...