I originally constructed the OakPark family in 1994 with seven family members. The fat stems invited decoration and four of the members had decorations on the stems, with one set on the upper-case keys and another on the lower-case keys. Only one member of the seven had true lower-case characters and two, one a shadowed style, had small caps on the lower-case keys. In 2018 I added an eighth style by separating out the inside of the shadowed style so it could be used in layers to provide color.
In March this year I revisited the family and did a major overhaul. I added an italics to the to go with the style that had true lower-case keys, and I added a plain or solid style to use in layers with the four decorated styles. However, the family had alternative shapes for over half of the letter forms, and the easiest way to make it all work was to take the four decorated styles and split them so each font had only one style of decoration in it. In the second row the first "A" shows the solid style, and the next eight show the decorated styles. I also added a hollow style because it could also be used in layers.
The picture below illustrates what can be done by using these fonts in layers. In the top line the solid style is red and forms the bottom layer. Above it in black is the decorated style. In the work "FUN" the hollow style is a top layer, also in red.
The word "WITH" has three layers, with the black solid font on the bottom, two decorated styles in the middle, and the hollow style on top. In the word "LAYERS" the last two letters have the solid style in red on the bottom and the hollow style in blue above it.