Here is an article from Wikipedia, the free encyclopedia:
All Roman numerals were formed by using a combination of seven basic symbols, each representing a specific numeric value.
This one is formed from 5 symbols in total.
And from 5 unique symbols:
||A single digit
||Graphic representation of five fingers
||Symbolises two hands joined together
||Adapted from a Chalcidic sign
||One half of the Chalcidic sign for one-thousand
This picture is unique unit of the whole collection.
May be this picture is exactly for You!