ME3 is a picture and object sharing app in 3D and is multiplayer. Create your own rooms. Share standard pictures from your phone, share JPG, PDF, 360 Photos and OBJ 3D files from your Mac. Rooms can be visited from iPhone as well as Mac. See www.me3vr.com for more details.
Visitors can join from different devices and see and talk with each other. Cardboard VR is possible but not necessary. All you need is a phone or computer. Rooms can be public or invite only.
100% free.