From HWY 82 and Carbondale: Turn south off HWY 82 and drive into Carbondale staying on the main road, which is State Highway 133. Drive south past Redstone and on to the turnoff for Marble, which is less than a mile before where the highway begins to make the climb up to McClure Pass at a definite switchback. Continue on rougher pavement to the town of Marble. Make a couple of left-right jogs to continue east to Beaver Lake. If in a passenger vehicle, you might as well park here. If you have 4WD, continue east past Beaver Lake and up a steep climb to the intersection of Roads 315 and 314. Take 314 to the right for Crystal. The narrow, one-lane road drops to a shelf section where visibility of other vehicles approaching from the opposite direction is limited. Try honking your horn to alert others to your presence. You'll climb back up a little after the shelf section then eventually drop down to creek level. It's a slow and rough 4 miles to the Crystal townsite. Park where you won't interfere with the private residences. It may be both polite and advisable to request permission to park.
There is no camping in Crystal, or at least, we would assume the residents there don't want people camping in their front yards. On the 4 mile drive in, there are a few at-large spots right alongside the road. There are three National Forest fee campgrounds back out on HWY 133. One is at Redstone, the other just after turning off 133 for Marble and the third just over the top of McClure Pass.