Last but not least, by creating a self-inking stamp, if you want to have two colors on the stamp impression, the expense of the self-inking stamp will be greater, while the two or multi-color alternative will not be present in the case of a rubber stamp.  

As a tip, if you are concerned with the company's image, consider creating a company stamp in two colors, as the stamp impression would seem professional to both your clients and suppliers.  

Average Types, Colours, and Sizes of self inking stamp: 

Type: 

Self-Inking or Non-Self-Inking 

Size: 

Round 12mm 
Round 24mm 
Round 30mm 
Square 24mm x 24mm 
Square 31mm x 31mm 
Square 43mm x 43mm 
Rectangular 27mm x 10mm 
Rectangular 30mm x 20mm 
Rectangular 30mm x 45mm 
Rectangular 30mm x 50mm 
Rectangular 33mm x 56mm 
Rectangular 38mm x 14mm 
Rectangular 40mm x 50mm 
Rectangular 47mm x 18mm 
Rectangular 59mm x 23mm 
Rectangular 60mm x 40mm 
Rectangular 69mm x 10mm 
Rectangular 69mm x 30mm 
Rectangular 75mm x 15mm 
Rectangular 76mm x 37mm 
Rectangular 82mm x 25mm 

Ink:  

Red/Blue/Black