1) Egg yolk blueprint

2) 4245362757481545366309154857

Breaking this string up into substrings of length 2 leaves numbers which are all divisible by three:

42 45 36 27 57 48 15 45 36 63 09 15 48 57

Dividing them by three leaves numbers which can be converted to letters (using A1Z26):

14 15 12 09 19 16 5 15 12 21 03 05 16 19

This results in the following string:

nolispeoluceps

When mirrored this gives the Latin:

speculo epsilon

Speculo means “mirror” in Latin.
Mirroring the character epsilon “ε” gives the number “3”.