This article describes Packing Boxes to Return Elo Products for RMA

Elo products originally ship in a quality box which can be reused in the event shipping the product is necessary.
To avoid voiding the warranty, use Elo Touch Solutions or equivalent packaging to return a product. This includes complete packaging, high-density foam and/or cardboard separators. Elo recommends packing devices as securely as possible, using bubble wrap and/or packing peanuts if necessary. Take pictures of the hardware before you package it, and of the packing itself, for reference, just in case there’s an issue in transit.

If you have discarded the original packaging you will need to obtain quality packaging from a 3rd party source.
Uline is probably your best option for finding appropriate boxes. Please click the link to be directed to Uline recommended boxes: here

Elo Touch Solutions recommends returning products by United Parcel Service, Federal Express, DHL, or another reputable freight forwarder. Touchmonitors 26” and larger should be returned on a pallet to prevent damage. To avoid damage, separate the monitor’s detachable stand, if any, for shipment.

Controllers MUST be returned in anti-static bags. If they are not, Elo Touch Solutions will consider them damaged and ship them back to the sender, as is, with no credit issued or repair attempted.

See our complete Return and Repair Policy here