(Kind of urgent) How to dry preserve a millipede?

[Crocodylidae]

So today I found out my first millipede I had since one year now died. I'm not sure why as the setup and alimentation seemed right and the other I have with the same setup etc is doing fine, I'm thinking (and hoping) it was just old age because when I first got him he was already a adult.
I would like to dry preserve him but I'm not sure how to do it.
I'm planning on putting him in a small glass terrarium with dirt, some wood and some fake leaves and basically preserve him on a piece of wood in it and try to get a natural position but I'm not entirely sure how to do everything yet, somebody suggested to me to put him on a piece of cardboard, maybe the wood piece if I really need it to position him and cover him with salt to dry him (I cannot use a freezer) and pin him for a few weeks, and then put him in the box I want him to be in. Is this a good way to do it? I only have 75% alcohol, and no resin or anything else.
I'm afraid he could still be alive and so before doing all of it, I want to be 100% sure he is dead, I'm not sure how to check for it though. He is limp, was found in a unnatural position (curled up head but ''upside down'' lower body) on the surface of the terrarium and does not react to anything since hours already, so I'm pretty sure he is and since he was a adult I doubt he would molt, but I'm still scared to pin it incase he is not fully dead.
Also, I only have normal pins, not insects ones, is this alright anyway?

Sorry for the amount of questions, I've never preserved any creatures before and I don't want to do it wrong,
Thanks if anybody takes the time to answer!

 

[Wesley Smith]

Unfortunately preserving millipedes in anyway doesn’t have the most satisfactory results. Dry preservation, if you do figure out how to do it will very quickly leave you with a dry, very (and I mean VERY) frail, exoskeleton. Liquid preservation will typically wind up with a pile of body segments on the bottom of the jar, the best way to preserve insects like millipedes is a resin pour. I know people have done this and there are tutorials though I’ve never done one myself and it sounds kind of difficult. I’m sorry for your loss and hope this can help in some way, even though I’m sure it’s not the answer you were looking for. Good luck.
EDIT: I Now see you mentioned you don’t have access to resin but unfortunately that’s the only way I know that won’t leave you with a pile of body segments, I’m really sorry to leave you with this.

 

[Smotzer]

What species is it, how big, how did it die?

Pinning millipedes is very straight forward, Styrofoam, an insect pin, or couple depnding on size and just allow it to air dry. It will become hard, dried specimens will be fragile. But its a very easy process. You do not need to cover in salt or anything like that. I am not home but will be on Monday and can send you a photo of a native millipede i have pinned and can help you through the process, that I have had for many years. Millipedes are much easier than centipedes. I will send you a PM!!