Fabricate is too high level for it.
Nothing however says the scrolls exclude spells with expensive material components. No 0-3 spells with particularly expensive components (Anything 100 or less is pointless since False Focus could dupe those) I'm aware of beyond Sepia Snake Sigil and Symbol of Exsanguination (500).
I see no level restriction.
This caster's shield always has one arcane scroll and knows the same arcane spells as the wielder. When the spell on the scroll is cast, another scroll of a spell the wielder knows randomly manifests to replace it. The shield has no arcane spell failure. The shield can also read magic. It will often debate with its wielder for the most devastating course of action, but does what the wielder commands.
This +1 light wooden shield has a leather strip on the back on which a spellcaster can scribe a single spell as on a scroll. A spell so scribed requires half the normal cost in raw materials. The strip cannot accommodate spells of higher than 3rd level. The strip is reusable.
We are looking at two different items then. The Shield of the Mage
has no references to the strip's limitations.
I see what happened. One reference used them interchangably, but they are entirely different items.
Caster's Shield lets you hold a scroll in it.
Shield of the mage is a caster's shield that regenerates scrolls from your own spell list, and one could make the argument that it inherits the limitations of the much weaker base type.