Not sure how much you want to follow in the thread, as it appears to be a bit of a length process. Weapon Riza is going for is the Model 38, a Sniper Rifle offered by Czerka which is so special because it is uniquely made, custom built for each specific customer.
Would likely be a long line of talk, deciding what's wanted, getting Riza measured, then having her go to a range they'd have specifically so they can test how she would be shooting with it, her form, and then sending off the order to be delivered and ensure it's a good fit before finalizing the thing.
Anyway, after saying all that, thread here:
viewtopic.php?f=82&t=2043000 credits, rarity 6, in EtU starting on page 40, right above the graphic