DDH "sofubi (soft vinyl) heaping" modding technique?

I've been coming across different ways to mod DD heads recently, one being the UV resin in DD skintones on booth.pm, but also I noticed a channel on youtube where someone takes pieces of scrap vinyl from DD heads and slightly melts them using a soldering iron or a wood burning pen into the eye holes on a DD. (You can watch the video here. It's in Japanese and this video in particular doesn't have subtitles, but he has a few other videos talking about the heat pen stuff that do.)

I thought it was really interesting and I wanted to know if anyone here has tried it! I'm planning on testing it out myself since I have a lot of ruined heads from failed modification attempts T__T I'll upload some pictures when I do.

I also had an idea to not only make smaller eyeholes for a DD, but you could possibly widen a chin or nose to make a more typically "masculine" looking doll for all the DDB fans out there... (I was going to try to do that for a female oc idea I had who just has a wider chin as well)

 

I bought the soldering iron from Hakko USA. The ones i got on amazon were too hot and burnt the vinyl. I’m practicing and butchered an old head practicing. I’m gonna try on a closed eye head coming from volks USA to see if that’s easier by drawing out the eye shape and trying building up. I like the soldering iron I’m using and it needs to be about 320-350F to melt the vinyl without burning it. 

If you give this a try make sure to use lung protection or at the very least work in an open air space.  You don't know what chemicals are in the vinyl that will get released when it heats up!

Also, I've seen similar mods with pullip and blythe heads where the modder takes shavings and dissolves them in acetone to create a vinyl putty.  You might want to see if you can look up info on that too.  You'll have much better control than if using a soldering iron and won't have to worry about burning stuff.