I thought it would be easy to design a mechanical watch once you understood the mechanism, after all they have been building them for hundreds of years and without the help of sophisticated machines like our printers. I was wrong!
the printed pieces are perfect but you have to deal with friction, inertia, human errors in assembly and to be able to have a working watch it took kg of filament, days of printing to correct the errors (or rather to eliminate the possibility of making errors in editing) but this is the result and I am very proud of what is my most ambitious project so far!

for assembly in addition to 3d prints you will need
-7 ball bearings 623zz
-m3 heat inserts
-m3 screws and washers
- fishing line for weight
-lubricant (I used a ptfe spray)
-2.5 kg of rice! (but you can replace it with anything else that has weight such as steel nuts and screws, sand etc...)

the result is not perfect, there would be great improvements by replacing the bearings with more performing models or by molding the gears in ABS to have a guarantee of greater durability and resistance to mechanical stress

ATTENTION! PETG pieces must be printed in PETG or more resistant materials!
printing them in pla will lead to deformations that will not make the watch work or worse, breakages and trust me, seeing the watch crash to the ground together with the weight and having to start printing all over again is not fun at all. you have been warned....

ASSEMBLY GUIDE

Before starting 2 simple warnings that must be repeated in all steps:
-lubricate all contact points and bearings!
-put washers on all contact points between the bearings and the inserts or screws! it is important that the bearing rotates freely without external friction

• insert all the inserts into the holes as you see in the following photos, also insert the bearings...the tolerances are very tight so you will have to be very careful not to deform the bearing.

  it is important that the inserts are perpendicular to the surface on which you have to fix them!
  be very careful, if you have a press for inserts it will help you a lot!

-assemble the frame with a little glue. you can temporarily fix the pendulum bracket by lightly tightening the screw on the side of the bracket

fix the gears to the frame following the sequence you see in the next photos

a couple of caveats. 

Check that each wheel rolls freely every time you fit it!
-on the spool of the last screw there is a hole to pass the thread from which to hang the weight. the wire should be wound counterclockwise. on that axis the hour wheel is fixed by pressure with a hexagon joint. the screw is only there to hold the pieces in place.
controls the weight rewind mechanism. by holding the hour wheel still and turning the spool counterclockwise the thread rewinds to rewind the watch. you can decide to fix the wheel with the screw or not. if you fix it everything will be safer, if you don't fix it you will have an advantage for rewinding the weight and setting the time as you will be able to slide the wheel forward and rotate it freely

this point checks that everything is working correctly. by attaching a weight to the wire (I tested with 2 kg) the clock should start working. the second wheel will begin to rotate slowly. as weight I used 2 packs of rice tied together with zip ties. Feel free to build any weight you like and fill it with any material. I chose rice as it was the simplest thing I had available and which had the most weight in terms of space taken up

-now you can fix the pendulum with the escapement mechanism!

follow the photos

the axis of the pendulum and the escapement mechanism must be parallel to each other! this is a very important step to make sure the mechanism works properly! if they are not parallel the gear wheel will not be able to apply enough force to keep the mechanism working. once you have found the correct position, tighten the arm with the upper escapement screw

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now you can fix the clock to the wall by passing the screws through the appropriate holes on the back of the clock. block the escapement with a screwdriver or something similar and you can assemble the pendulum (sorry about the photos. but it was the only place already ready in the laboratory.... the drill is broken so I had to do my best XD)

assemble the pendulum by connecting the various parts with the PETG connectors. on the last piece insert the bob and the nut used to adjust the height. 
in theory the weight of the bob should have no influence on the functioning of the pendulum. in practice, however, the friction of the various pieces and the air influences the functioning of the pendulum. you will have to find a balance. Personally, with 120g of rice inserted inside I can create that bit of inertia in the piece which makes operation more fluid

-The lower screw is used to adjust the height of the bob. theory dictates that for the period of the pendulum to be equal to 1 second there is an arm (measured from the center of rotation of the pendulum to the weight) of 1 meter. the screw is used to make fine adjustments and obtain a period as close to 1 second as possible. you will have to adjust it once you put the watch into operation

Now the hard part
as you can see in the photo, the axis between the center of the seconds wheel and the center of rotation of the escapement mechanism must be absolutely perpendicular to the ground!

if the axes do not coincide the mechanism will stop! depending on how much the axis is moved you could have a functioning of a few minutes (until the force you put on the pendulum to start it is dissipated and the moment of the wheel is not enough to start it again) or no functioning at all.
I advise you to get a plumb line to briefly check the alignment. then you will have to make small movements to ensure verticality. a very reliable index to verify that the mechanism works is the noise of the mechanism. if it doesn't seem regular you will have to move the escapement arm until you get almost perfect timing. when you have found the right position, fix the pendulum with the screw on the side of the bracket.

in a first version of the clock I had fixed the arm to the frame in order to be sure that the pins remained on the same axis....I hadn't calculated however that I'm not that precise with the drill and fixing the holes for the entire structure millimeter level is practically impossible. so no it is not possible to have a plug and play version of a similar watch...you have to spend time adjusting it

now you can attach the hands and screw caps and you're done!