I have about 10-15 large boxes from moving, for large keyboards and musical instruments. Most of these still have the packing materials in them (bubble wrap, packing peanuts). Having moved my studio here from TX, I have boxes that will fit 61-key, 76-key and 88-key keyboards, and some other more rectangular boxes, including larger rack gear boxes. These are great for shipping something you sold on eBay, without paying $50 or more to the local UPS or Pack&Ship store to custom package. $5-10 for each box, depending on size. Let me know what you need, will see if I have something to fit it!
do NOT contact me with unsolicited services or offers