Yes, you can epoxy a piece of tubing into the lanyard hole. Go with a slightly larger hole than the outer diameter of your tubing in this case, so the glue/epoxy has someplace to go. Like if your tubing is 7mm o.d., go with an 8mm hole. Coat the outside of the tube with a thin layer of adhesive, then slip it into the drilled hole while the slingshot is laying on its side (so the piece of tubing sits vertically), and then let it cure overnight before sanding/finishing. You can also drill a hole the same size as the o.d. of your tubing and then and then countersink the hole slightly. Then when you put the tubing in place you can flare the ends to hold it in place. This also gives a neat appearance. You need some sort of flaring dies and a bench vise to do this though, so it's more expensive. Professional flaring dies look like this <a href="http://usaknifemaker.com/tube-flaring-dies-for-fastening-handles.html" class="postlink" target="_blank" rel="nofollow">CLICK HERE</a>, but you can also cut the heads off of large steel screws (like large drywall or wood screws) and use them in the same manner (as long as the tapered part of the screw heads are larger than the inner diameter of your tubing.