That sounds fun. What are you thinking? Maybe have the sub stand under a bucket with a hole in it. Plug the hole with a plug that has ropes on each side. Attach one side to a weight and give the sub the other side so they have to continually pull on the rope to keep the bucket plugged. Then fill the bucket with slime and wait for the sub to get too tired to hold the rope any longer and are forced to slime themselves
Having had a number of shockingly unsafe gunge tank prototypes sent to me in the past few months I feel I should start this with a brief safety notice.
Obviously combining WAM with bondage and predicament bondage introduces some additional safety concerns people should be mindful of and take sufficient precaution with.
Ropes and knots tied on well lubricated bodies are much more likely to slip or slide to potentially rest against certain blood vessels and cut off circulation whoever is rigger should regularly check this hasn't happened.
WAM substances naturally result in slippery floors. Tied up people cannot extend arms to catch themselves or try break their fall. They could land at bad angles and you certainly wouldn't want certain body parts (especially the neck) getting caught on ropes mid fall. Slipping and falling whilst attached to things like nipple clamps fixed to some other thing won't be fun either. Think about the probability of slipping and falling in any given bondage or predicament position when combining with WAM.
Here's a couple ideas
1. Hogtie them on the floor, have them lift their head up off the floor. Place a pie on the floor. Let them choose between straining their neck maintaining their position or lying face down in pie whilst in bondage.
2. Have them lie naked on the floor face up. Fill a beaker/plastic cup with a sufficiently yucky WAM substance (Baked Beans for example) and balance it on their forehead. Have them maintain their position trying not to let the cup fall over. If it does refill it. If they're really good and you are getting impatient break out the feather duster to start tickling body parts They're not ticklish? Break out the remote control vibrating love eggs
3. Have them kneel in front of a very full bucket of mess. Attached nipple clamps with weights dangling at sufficient length that should they lean forward to dunk their head in the bucket the weights will rest upon the ground to give their nipple a rest but short enough that taking head out of the bucket leaves the weights dangling and pulling. Have them decide between dunking their head in mess and enduring the nipple weights.
4. Stick/fix a drawing pin/thumb tack to a hair accessory (make sure it is very secure) and have them wear it. Have them hold a balloon full of mess over their head. See how long they can hold it before they let it pop.
You are quite right, we have made a few video's featuring Predicament Bondage and even a suspension in Chocolate. Choice of rope is super important and being ready to cut the model down is key. Some of the most fun ones were when we bent a model over the edge of the mud pit (at the deep end) attached weights the her ankles and then pushed he half over the edge to how long she could hold her self up before going in face first. Dressed as a school girl of course! LOL
Planking over pies - how long can they hold out until they faceplant the pie (can also be done in a pool of something slippery too, makes it a lot harder, and messier) Do put something soft underneath, otherwise, it can cause a less enjoyable pain if they slip!
Even something a lot more simple - have it where they are doing something uncomfortable and to get out of it, they have to plead for in this case you to gunge them
I don't know why I didn't mention this right away. I had this custom done where the girl was cuffed and the key was at the bottom if a bucket of gunge. And if she wanted to get out, she had to fish out the key with her mouth.