You're much more likely to get a meaningful response if you say what part of the world you're from. I've looked at your avatar but can't see any region - maybe it's my old eyes.
Were I to assume you are from the UK then I use these guys,
Custom Scratchplates & Pickguards -100% bespoke, handmade, and guaranteed to fit perfectly! - TinyTone I've used them several times and each guard has been spot on. They prefer you to send your old guard as they'll be able to match everything exactly including screw holes.
There is a guy on Ebay who is supposed to be really good by the name of
earlpilanz. I've not used him as his shop was shut due to moving home when I wanted a PG so I went to Tinytone and have used them ever since. If you are in the Americas then I believe EP and Tinytone will ship to the States etc.
There must be tons of US PG makers so do a little research on reviews if you are in the States, you'd probably get better VFM from stateside suppliers rather than the UK ones as you'd have to pay shipping to the UK for your existing PG then shipping back.
If you are in Europe then unfortunately tinytone do not ship there because of the red tape that Brexit has caused.Don't know about earlpilanz. Again look at local suppliers if you are in Europe, Asia or Oceania.
Note that to put a bog standard MM pickguard on the Z3 wont work as it's a different shape and the truss rod adjustment cut out will be different too.