You have created a small metallic shell that a spirit can inhabit, allowing it to function as your familiar. The familiar uses the same rules and options for a familiar conjured by the find familiar spell and has the statistics of its chosen form but is classified as a Construct instead. The construct familiar gains the following benefits, in addition to what the chosen form allows; their AC increases by 1, is immune to poison and disease, and is immune to the following conditions charmed, exhaustion, and poisoned.

If you already have a familiar conjured by the find familiar spell, then it may become the construct familiar instead. This construct also counts as a familiar for the find familiar spell.

If you can't find friends or they're just unreliable or also not expendable, then just make some. At least, that's what I always say.

– Gilman Fizzlewix