Bound
Gagged
Hooded
Wired
Use of Sound
Use of Linings

Related
 No Wank
 Cum Control
 Confined Spaces
 Sensory Depravation
 Breath Control
 Mind Control
 Hypnosis

Once secure in the box you can then consider:

• How well be might be gagged.
  Because of the restricted movement of the head, he would not be able to move his head to clear and saliva build up. In this position, a ball gag is the worst one to choose being almost dangerous if left unattended. The better ones to use are more like Muzzles or a pecker gag, something he can chew on.
  
• A Gas Mask will give him a nice enclosed space.
  The air hose can easily go outside for use in breath control but in that enclosed space you can smell the rubber or leather, or the musty smell of bound slave sweat. You would have to be aware of the air quality so that there is an ok level of air quality - it might be ok initially, but over time changes.
  The same is when you might lock your animal up in other small confined spaces like a cupboard under the stairs the works as a jail cell/kennel. The gap under the door will not provide the air for long and could be blocked by his dog bed. He will develop headaches and the air quality goes down. Likewise, controlling his air supply to include other smells or Poppers/dope smoke for example will have a good effect, but still balance it with quality air.
  The Gas Mask will enhance the quality of 'small confined spaces', it has a sound feedback, as the valves open and close as you breath this can act like a bio-feedback system, re-enforcing the sensations and feelings of your predicament. I like the Russian GasMasks that almost encase the head in a rubber balls, as you can also fit a rubber pecker gag to the slave, if you just wet the area where the mask and gag strap meet, the air seal is maintained.
  Hoods
  These can be an even more intense experience, like your head is in bondage. Try the experience when you are hooded no eyes, mouth is gagged and then you have a snug crash helmet put on, the smell of poppers might come in as the visor closes to keep you into the enclosed space.
  Caution: There is a lot to take off if you gag or choke. Soon too much poppers can quickly be a problem, let alone using drugs. It is better to under use a technique that to over do it, long term SM is best achieved with subtlety. What happens if there is an anxiety attack or a moment when claustrophobia kicks in (it can happen out of the blue). What you don't want to happen is have the slave turn off of something due to a bad experience.
  There are all to many slaves out there that have had 'bad' 'Master'  that have 'ruined' the slave, which results in there being a lot of remedial work with the next Masters as he has to fix damage done,
  
  

• Fitting suitable electrodes to the slave.
  This can give him hours of stimulation, as the electricity plays with his cock and balls, with his tits, and fucking his hot ass hole. Choosing the right Electro butt plug is essential as the slave will be sitting on it, so you don't want it broken (they are not cheap), to break contact or damage him. The ideal Electro butt plug is one that you hardly know is there until you switch it on.
  In addition, that Master could use a Remote Trainer on the slave to torment him, to spook him.
  
• The use of sound.
  Here you can use head phones, so you can cut off all other sounds from outside or from inside. These work well with some Gas Masks and not others.
  Likewise you can sound proof the box so he is focused inwards and isolated. Yet imagine the feelings he would have when he can hear his Masters walk past, has he come to rescue me, only to find that the Master kicks the box with his boots and verbally taunts him. The slave can be aware of sounds and trying to make sense of them, you can play on this for hours.
  You can have a speaker phone in the box, you can play white noise to isolate him and help him 'trip', you can play suitable hypnosis tapes, you hook  him up to 'brain washing' mind control programs.
  
• Lining the box
  Rubber lining the box can all to the smell and feel and the experience. One slave I know of had a bondage box much like the one above, that was rubber lined. He was into filth and toilet training. He would be kept in there with a full bladder and butt, and left so left in the eventual filth that was to follow. Likewise he could be bound in just a pair of tight 501's, the rope secure around his pelvis the way a rock climbing harness is snug. When he eventually mess himself (like a Diaper scene I guess), being left there helped 'Gross him out', and locate the slave deeper into his depravity. All of his senses would be swamped by the smell and sensations.
  Leather lining the box your can feel that on your bound naked skin, or you hear it creaking against the leather Chastity Shorts that are locked on you, this to is dead horny
  
  

By now you get the idea, you can understand the frame of mind that he will come out in. If the box can open in two sections, you can keep his head enclosed, and open the body section. The dividing section at his neck can act as a light block. You could lie down comfortably on the bed next to him, your dropping comfortably down to his crotch and you can play with his balls and cock very precisely - and very frustratingly - for hours. And again there is absolutely nothing he can do about it.