Here is the numeral one(1) in lineart for you to colour.
Below are two examples of colouring done to the number 1.
The number 1 has been digitally filled with pattern. If you desire to do this manually, you can doodle\draw some patterns on the number 1 or cut a patterned paper using the number one as a template and then layer it on the number 1
The number 1 has also been bevelled digitally. This effect has been done using blur. You can create this effect manually using different shades of a particular colour.
Lineart or drawing
Bevelled
Pattern fill