There are ten symbols: Llama, Pine Tree, Shooting Star, Question Mark, Six fingered hand, Broken Heart, Tent O' Telepathy Star, Ice, Glasses, and Stan's fez symbol. Everyone knows Dipper's Pine Tree, Mabel's Shooting Star, Soos is the Question Mark, Robbie is the broken heart, Gideon is the star, and Grunkle Stan is the fez symbol. The rest are up to consideration.

Ice- this symbol is the most vague one. Some say it is Wendy because she is 'cool', but I don't think that is very accurate. I believe that the Ice Bag is Blendin Blandin, Time Anomaly Removal. Why? Well, he was first introduced by running into Dipper, who was carrying an ice bag. Another person possible is the Time Baby. Okay, before you think I've lost it like McGucket did, just hear me out. Time Baby is frozen in an iceberg. Also in Dipper and Mabel 's guide to nonstop fun and mystery, a code turned out to be that the Time Baby is worried about Bill.
Other than that, it's just opinion.

Llama- I say it is Pacifica. The reason being is the llama is in the opposite direction of the llama Mabel wore in Headhunters. Thus, saying Pacifica is the opposite of Mabel. But, they're friends now. Well, opposites attract.

Glasses- this one could be Ford because they are the exact same glasses he wears.

The six fingered hand- also is Ford but he can't have two spots, can he? Unless this is the journals. OoO

The Cipher Wheel will be used either to destroy/ imprison Bill or summon him like Gideon did in Stanchurian Candidate...oh spoiler alert.
The people who the wheel consists of will possibly be used to unleash or stop the dream demon we all know and miss.
(I'll admit it, I missed him.)

Thank you, once again for reading this pile of rubbish I call a 'book'. Comment your thoughts!
Yroo rh xlnrmt lm Hvkgvnyvi 7gs. :-)