I presume the customer is asking for permission to sell 3D printed copy’s of the design (not necessarily reselling the 3D files)?
Keep in mind selling items that are branded “Baby Joda” and associated with trademarks “Star Wars” are illegal, unless you have a deal with Lucas Arts/Disney.
I’m not suspecting your doing anything illegal and if you do its non of my businesses, but just be careful. Your asking this type of question here looks like you don't know that much about licensing?
Remember, CGtrader is mentioning in the site user agreement “users are not allowed uploading copyrighted materials”. Some people here probably presume CGtrader is some sort of umbrella they can hide under, but CGt will just cooperate with law enforcement if they get requested to do so (That's one of reasons they need full ID info when we become seller). There is probably lots of copyright infringement going on here but its not safe to believe its ok because of it, sooner or later some will probably regret it.
Anyways, if you indeed have permissions/license to use the trademarks and designs, you probably still need additional permissions to transfer that license to a third party (almost never going to have that permission). If this third party gets invalid license transfer from you (made without Lucas art/Disney permission) and he gets in trouble with Lucas art, then both he and Lucas arts can demand all damages from you. This could include fees to pay back customers who payed for the illegal 3D printed merchandise and the cost to destroy the copy’s, the damages and cost to produce the 3D printed copy’s, etc. Basically Lucas art would demand correcting the damages from your customer and in return your customer demands all correcting of damages from you.
It could just be a total nightmare and life long in debt scenario, even worse, depending on the country your in, a prosecutor could probably call it international illegal trade in counterfeit products and in addition demand a hefty fine or even jail time?
