About 260 years ago, Benjamin Franklin designed a clock with one hand that told both the hours and minutes. You can read more about it here:
Aside from the 3D printed parts you will need (approximate):
1 yard long by 1/4 inch wooden dowel
3mm stainless steel rods (search for 3mm RC rods)
$2 in US pennies for the drive weight
1.5 yards of mason line
a paperclip or something else for the drive weight hook
I was inspired to create the clock after finding that the clock faces had been modeled. Here's the summary from jamcultur from his "Benjamin Franklin clock dial":
"Franklin's design never caught on, but clocks based on it have been produced in limited quantities from time to time, for example, an electric version by Paragon in the 1960s, a weight-driven version by Thwaites and Reed in the 1970s, and a wrist watch by Meistersinger in 2015. For more information, see http://www.ablogtowatch.com/meistersinger-benjamin-franklin-watch/
My 3D printed version of the Franklin clock dial is very similar to other versions, except that I replaced the Roman numerals with conventional numerals. I designed it with raised lines and numerals so that I could color them with a sharpie after printing. The small dial is for the seconds hand."
In addition to using the clock faces from another project, I also used the escapement and pallet from A26's "Clock"
Please see the TinkerCAD link below for a 3D assembly representation.
You have to glue the minute/hour rod and the seconds rod into their respective gears so that the hands rotate with the gear. The center gear can simply spin freely around the rod, but it might stay aligned better if it is glued to the rod as well.
If you find the gear train too tight, then possibly use a drill press to make the holes just a tiny bit larger. Everything is fairly tight as it is because there is so much weight on so many small teeth in the gears that it may slip if it's too forgiving.
For the drive weight, I tied a string to one of the large spokes in the hours/minutes gear. Since each revolution of that is four hours, you don't really have to wind it too much to get it running for a long time. Also, you may not need to fill the penny weight up entirely -only what you need to keep things moving.
For lubrication powdered graphite is your friend! It really makes a difference in keeping the friction low on the plastic and metal.
See TinkerCAD for how to assemble