The Lenovo Explorer is an awesome (and inexpensive) way to get into VR, but it lacks integrated headphones. Meanwhile the HTC Vive has an optional pair you can buy... for $99.
I had a cheap pair of headphones laying around that looked like they'd be easy to modify into something I can mount on the headset, and after a few hours of testing here it is.
These are the $15 headphones I used (Kanen i50):
The mount allows you to slide adjust tension on the clip and the headphone mount so you can slide them forward and back, as well as up and down for best fit.
These headphones have a mic but it is not on a boom, so I used some zip-ties to hold it in place and let it hang down. My testing shows it works fine for voice controls and chat, and it stays out of the way.
Uses eight (8) M2 8mm screws (or similar)
I recommend to use at least 4 outlines/perimeters if using a 0.4mm nozzle to make sure they are strong and will hold up to all the activity.
Print two of each piece. Assemble with M2 8mm screws. See photos for help.
Disassembling the headphones consists of removing the dozen or so screws from the black plastic mounts and carefully cutting the vinyl band along the top. Be careful not to cut the cable that connects the speakers to each other.
I left tolerances tight for the screw holes so you will probably need to drill them out or use self-tapping screws. This is by design in case you have different screws handy, you can use anything as long as it fits. I recommend drilling out the holes in the lid and clip bottom so the screws slide in without resistance, but letting them grip tightly into the main clip body.
The small wire that connects the two speakers together can be run along the back of the head strap and hidden under the rear foam piece (between the Velcro).
I made a small loop for the microphone and zip-tied it together so it hands on the left (see photo), then ran the cord through the metal loop. I then used a bit of braided cable wrap to hide the extra length cable along the back and plugged the headphones into the helmet.