I only use number shapes for 0-9, but there is something called the Shaper System, if you want to continue past 9 with shapes. Another alternative is an association system. You might also be interested in the How to Memorize Numbers video.
(My numbers system is described here.)
You can use multiple consonants per digit. I use R for 4, but it can also be TH when it’s the last digit of a 3-digit number (in a 3-digit system).
Example:
| Number | Sounds | Image |
|---|---|---|
| 044 | S-A-R | sardines |
| 054 | S-AI-TH | scythe |
(The middle digit is a vowel for me – my example is just to illustrate that the 4 can have two different sounds.)