I've been writing my scroll layout handout for the coming Lonely Tower Scribes' class. While it's too detailed for here I thought a few design tips might be appreciated.
Picking your inspiration
I first choose a medieval style relating to the recipient's persona or interest. If that's not possible because time is short and I can't find that information on Facebook or through their home group, I base the design on the Monarchs' persona.
Choosing size and shape
I consider the scroll's text when planning the layout. It's a blessing when I connect with the wordsmith prior to its writing to get an idea of the planned style.
If it includes poetry I will need more space to display the text lines appropriately.
If it is a legal-type text may opt for a horizontal "landscape" format as in later period illuminated patents.
Sometimes I design the scroll as if it were a bifolio, two book pages opened flat. While useful for lengthy text, it divides the "picture" in half, rather than the more eye appealing thirds.
Considering my available support, I base the size on a standard frame and mat size. It is a courtesy that encourages care by prompter framing.
Because the eye follows lines I emphasize them. Even the natural Renaissance illuminations have tiny outlines, although I prefer the earlier styles more dramatic lines.
I like curved lines for design interest. They're more fun to create than the strength giving horizontal and vertical lines. I control their pattern, especially when creating rinceaux, which can overwhelm script.
I try to balance "white space" or negative background space and my art, the positive space. I like white space because the scroll feels less overwhelming, busy or chaotic. Too much white space and it feels boring and lifeless. I consider this balance when planning room for the Monarch's signatures and standard matting.
I love whitework because of its intense value contrast. I also like dark lines within light areas. Both contrasts attract the eye. For color contrast, I use heraldic tincture rules to deliberately choose my colors. They were ingrained in medieval life, so you find them used in most manuscripts.
Balance is a key to design. If the layout design is off I simplify. I remove distracting elements or peripheral interests. When the period style is busy I choose only necessary motifs to combine for a totally original work.
Those are my main layout considerations. Some begin with the period resources, some with the recipient. All combine to make the final scroll.