Start with a bracket and alternate case. Make sure to end with the proper bracket. 

List of pairs

Aa Bb Cc Dd Ee Ff Gg Hh Ii Jj Kk Ll Mm Nn Oo Pp Qq Rr Ss Tt Uu Vv Ww Xx Yy Zz !1 @2 #3 $4 %5 ^6 &7 *8 (9 )0 <, >. ?/ ~` _- |\ {[ }] Ää Çç Ññ Öö ẞß Ğğ İı Şş

Supported:

Basic Latin

More Latin

Latin-A

Latin-B

IPA Extensions

Spacing Modifier Letters

Combining Accent Marks

Greek and Coptic

Cyrillic

Hebrew

N'Ko

Cherokee

General Symbols

Currency Symbols

Variation Selectors

Specials

Partly Supported:

Laos

Hangul Jamo

Block Elements

Circled Letterforms

Its not finished yet...

Will release the first open-source variation for everyone to expirement at 4000 glyphs.