Is the modeling pack effective?

Looking at the post Modeling pack I've been seeing a lot of people doing it themselves!
I have received modeling packs for cooling after procedures, but

I didn't know I could do it myself haha

For those of you who do it yourself, which brand do you use?

If I buy it in powder form, can I only buy it in large quantities?

If anyone uses modeling packs, please share any tips you have!