HHmmmm, yeah. Resin would work. A two part product poured on just enough to soak into the threads. Also, a water repellent spray like Scotch Guard could work. It would repel water and soil without making the coasters stiff. There are several products like Scotch Guard, one is called Camp Dry. Look in the camping section of your local store.
Are you familiar with a "vacuuform" ? It was a Mattel toy made in the late 60's. With it kids could make toys out of plastic. One half of the machine would heat the plastic sheet, then when flipped over the sheet would be pressed down onto the chosen form and a pump would vacuum seal the plastic tight over the form.
There are people who do just this on a larger scale in their own homes. They buy the sheets of plastic and heat them in a low oven. Then they use a home made vacuum table to mold the plastic around what they want to copy.
You could do this using things you have right at home. Many things come in plastic blister packs. Save some of this plastic, the flatter the better. These plastic sheets can be heated in your oven or with a heat gun. Then, when hot and pliable the plastic sheet can be formed over the plaster skeleton by pressing down and pushing the plastic by hand around all the curves and crevices. The plastic can be reheated by using a heat gun on whatever area needs to be redone.
This will only make a copy of one half of the skeleton. It will come out kinda like a jelly or candy mold. You would have to make another mold of the 'back' of the skeleton for a 3D copy. The two molds would be filled separately then the two chocolate halves fitted together using melted chocolate to 'glue' them together.
I hope this helps you. let us know how it comes out!
How water tight do you want this to be? Will this become a coaster, hot plate or actually applied to a wall as tile? Try using a spray on adhesive. This will help with the bubbling. After spraying the adhesive, use a can, cup or roller to burnish the postcard onto the tile. The type of printing ink on the postcard will affect what kind of sealer you use on top. Try a spray can of sealer. Try both water based and enamel/lacquer types. One of these is bound to work. I think the decoupage stays wet too long and has to be brushed on which causes the ink to smear. Something quick drying would work better. Also, consider resin as a top coat. A two part resin that you mix and pour might work, especially after sealing the postcard to seal the ink. Just a few ideas. Keep us posted on what works and what doesn't!
Has this been fired, or is it greenware? He's very creepy, someone will love him! Zombies are very popular right now so you will find a taker. I think he needs more details, like stitched up cuts, and some gory decaying bits. He could be a paperweight or become a doll, a finial for a bed or walking stick, or a topper for something else. He has potential!
I love Crayola Model Magic craft compound. It's light weight, not toxic, air dries and is kinda bendy. It has so many uses and potentials. The draw back has always been that if it dries before you want it to then you are out of usable clay! When it was first introduced, they sold it in plastic bags that could be zip locked after opening. Too many times I would come back to use the clay and find it all dried up, even after closing the bag! I have even found unsold bags in the store that have dried compound in them!! No point paying for something you can't use!
Things got better then they started selling them in small and large tubs. The shelf life of the clay increased. However, I never fully got over being curious about how to soften the clay for reuse. I am a cheap skate and live frugally. I wanted to be able to soften and reuse this clay!! After finding a large lump of newly purchase white just laying around (thanks, kids!) I got determined.
I popped some in my mouth to see what it tasted and felt like. It is slightly sweet and has no chemical taste. It is slightly gritty like toothpaste, a very fine grit. I inspected the newly softened blob and could see cellulose like fibres. It stuck together slightly, but not as much as the original product. I then decided to do the same thing but on a larger scale.
I put some small pieces in my little food processor and ground it up into small bits. I then added a small amount of very warm water and mixed it further until it formed into a ball. I then took it out and added a dollop of wood glue (any white glue would work) and mixed by hand. At first it was lumpy like oatmeal, but after about 10 minutes it became smooth. It is nearly like the original state, just not as fluffy and air filled. Hallelujah! I have found a way to soften and reuse this stuff!!
Feel free to do this yourself. You might find adding the white glue is unnecessary, but it does help it to stick together better. My conclusions are that this compound is made of a very fine cellulose mixed with calcium carbonate powder and some polymer glue (white glue). How they get it fluffy is a mystery. I don't think they use baking soda, the clay is not salty at all. They may use a gas when mixing or may just beat it and incorporate air. Well, I gotta go. I have some model magic to play with!!