For the bondage device...cheap and simple. Go to a hardware store and buy a few feet of thin metal chain and a couple of padlocks. I bet the whole thing would be less than $10.
Wrap the chain several times around your wrists to spread the load, and it doesn't need to be too tight - so don't risk limiting the blood supply.
For a "timer", I found this interesting variation on the ice cube method.
http://www.boundanna.com/html/en_tech_iceinbottle.html
You can keep a junior hacksaw close by as a safety backup - but cutting through chains will take a while!
OK...so now to make it more "challenging" for you.
I'm not sure if this will work, but recently Sebastian reminded me about the use of ginger root applied to sensitive areas.
Here's my idea.
You can buy "cock-shaped moulds" pretty cheaply to make novely ice lollies and stuff.
http://www.lakeland.co.uk/13025/Ice-Lolly-Moulds
Carve a piece of ginger for anal instertion. However, before you insert it, make a batch of gelatin soution (make a really strong batch that will set quite firmly).
Use the ice lolly mould to coat the ginger in gelatin, and let it set. So now you have the ginger coated in a stiff gelatin layer.
(Note that you need to carve the ginger with a "knob" on the end so there's no risk of it slipping right inside you.)
So here's what I think would happen. You'll need to figure out a "timed bondage" technique - like the classic "key in the ice cube" method.
But before you lock yourself up, you slip the gelatin-coated ginger into your ass. Then put on a pair of Speedos or something really tight so you can't wiggle it loose.
At first nothing will happen because the gelatin is protecting you from the ginger, but gradually the combination of the anal lube and your body heat will melt the gelatin and expose the ginger. But there's nothing you can do about it until your time is up, and you have the key to unlock yourself.
It's like having a ticking time bomb in your ass
If you wanted to keep the ginger "coated" for longer, maybe use chocolate instead of gelatin. As long as you stick to materials that are edible I don't think there's a safetly issue. Chocolate with higher cocoa content will take longer to melt, and the cocoa fat will probably protect you from the ginger for longer too.
Another idea - instead of ginger you could make a gelatin "ice lolly", but then use an apple corer to hollow out the center. Fill the center with Deep Heat (I think you Americans call it Icy Cold, or something...it's a cream for muscle strains). When the gelatin melts you will feel it!
you might need to experiment a bit - I'm wondering if either gelatin or chocolate is strong enough to allow the lolly to be inserted in your ass without breaking right away. Maybe other folks would have a suggestion for some materials that would work.
Is that the kind of idea you were looking for?
Cheers,
Stanley
