You might find the
Unicode Upside-Down Converter useful.
It converts "0123456789" to "68Ɫ954Ɛ210". Unfortunately, they haven't found a decent upside-down '2' yet.
Seems to have some odd teething troubles ...
THE QUICK BROWN FOX JUMPS OVER THE LAZY RED DOG. Fill my box with five dozen liquor jugs.
becomes
˙sƃnɾ ɹonbıʃ uǝzop ǝʌıɟ ɥʇıʍ xoq ʎɯ ʃʃıℲ ˙⅁O◖ ◖Ǝᴚ ⅄Z∀⅂ ƎH⊥ ᴚƎᴧO SԀW∩ſ XOℲ ᴎMOᴚξ ⋊ↃI∩Ό ƎH⊥
I don't see why they use 'ʃ' for 'l' when 'l' is already symmetric in many fonts.
(Yes, it's 5:18 in the morning in Houston. Rare for me to be up this early.)