Get one made out of plastic. There are a bunch of open-sided ones that you can get for $10 or less that fit in your pocket:

http://www.hypergridbusiness.com/2016/06/13-open-sided-vr-headsets/

The Noton is a good set for under $10, too, it's missing some features, but then, a cardboard is missing ALL features, so it's a decent trade: http://www.hypergridbusiness.com/2016/03/review-noton-super-cute-low-cost-cardboard-alternative/

And the FiiT VR is one of the best, most user-friendly headsets on the market, and it starts for under $20:

http://www.amazon.com/Great-Polly-Virtual-Innovative-4-0-5-9inches/dp/B01E4HQPBW/ref=sr_1_9