This is a clock.
Here numbers become directry clock face, so font design (Trajan) of the numbers determines design of this clock.

Also the face is rounded as part of sphere.

There is another version of this clock.
http://www.thingiverse.com/thing:1021435

I bought the clock movement from Amazon Japan (3.20$)
http://www.amazon.co.jp/gp/product/B00NL3GDAO?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00

Dimentions of it are 55×55×16 mm.

Sept. 25, 2015
Some parts were updated (body, face, arrow, arrow2(wider)).

I am using DaVinci 1.0 3D printer by XYZ printing.

Layer pitch is 0.3mm.
Normal speed and normal shell thickness.

No raft. No support.
With stick paste(Tombow, Shiwanashi PIT).

480 minutes to print. 60 minutes for shaping, constructing and sanding.
40m for ABS.

Use jig to place numbers to correct position

Other parts,
1 clock movement module (typically 3-4$)
1 AA battery

Also if you have ø3.7 and ø5.5 hand reamers, they should help you to make hole on arrows accurately.