While subject to SG approval, things like Arcane Connections and Holy Relics are often encased in other materials. For AC this would normally be done when you are "fixing" it. In fact for small fixed AC, this is the only way they would be useful and stable.
If you fixed a hair, a bit of skin, a drop of blood, or a piece of leaf for example they are all extremely small and fragile, which not only makes them easy to damage or lose but also very hard to work with. Encasing them in something not only makes them much tougher, but also a more handy size for working with and preventing you from losing them. How you encase them could be anything from a small metal or glass vial, a chunk of quartz or amber, or something like a rosary bead.
Something like this can even be done for larger AC while you are fixing them. The original AC is stabilized during the process and there is no reason to actually even need the whole thing. The connection is stabilized while conducting the process, which prevents it from decaying or forming a different connection. For example a large rock (say about 11lbs/2kg) might serve as an AC to a location, but if broken its original connection might change from the location to the other fragments. The link to the original location is "locked in" while it is being fixed so that it does not change or decay, even if only a part of the rock is used in the final Fixed AC. So the Magus could form something the size of a marble or chess piece which is easier to carry and work with.