Not sure how doable these are. But for example the trex head from the minifigure line was made so collected a list of many of the animal parts. If you make a piece make sure to check it does not exist since this long list.
triceratops
https://www.bricklink.com/v2/catalog/cat...#T=C&C=155
snake short neck:
https://www.bricklink.com/v2/catalog/cat...2#T=C&C=34
snake long neck
https://www.bricklink.com/v2/catalog/cat...9#T=C&C=89
snake 2 heads
https://www.bricklink.com/v2/catalog/cat...02#T=C&C=5
Unicorn:
https://www.bricklink.com/v2/catalog/cat...#T=C&C=157
ox
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=68
bear
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=88
bear 2
https://www.bricklink.com/v2/catalog/cat...4#T=C&C=71
bear 3
https://www.bricklink.com/v2/catalog/cat...#T=C&C=153
Mouse:
https://www.bricklink.com/v2/catalog/cat...#T=C&C=150
Llama:
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=2
Lion mane:
https://www.bricklink.com/v2/catalog/cat...#T=C&C=110
fox
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=4
chick
https://www.bricklink.com/v2/catalog/cat...71pb02#T=C
Giraffe
https://www.bricklink.com/v2/catalog/cat...#T=C&C=103
Horse:
https://www.bricklink.com/v2/catalog/cat...2#T=C&C=42
elephant:
https://www.bricklink.com/v2/catalog/cat...57pb01#T=C
Dragon:
https://www.bricklink.com/v2/catalog/cat...94pb01#T=C
cat
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=11
angler fish
https://www.bricklink.com/v2/catalog/cat...07pb01#T=C
hammer shark
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=86
shark
https://www.bricklink.com/v2/catalog/cat...13pb02#T=C
shark punk haircut
https://www.bricklink.com/v2/catalog/cat...9#T=C&C=39
wolf
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=85
tiger
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=4
snowman
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=1
reindeer
https://www.bricklink.com/v2/catalog/cat...#T=C&C=150
racoon
https://www.bricklink.com/v2/catalog/cat...2#T=C&C=86
wolf 2
https://www.bricklink.com/v2/catalog/cat...5#T=C&C=85
wolf 3
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=11
tiger 2
https://www.bricklink.com/v2/catalog/cat...83pb03#T=C
rhino
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=86
skunk
https://www.bricklink.com/v2/catalog/cat...5#T=C&C=11
octopus
https://www.bricklink.com/v2/catalog/cat...8#T=C&C=48
lobster
https://www.bricklink.com/v2/catalog/cat...=4#T=C&C=4
rabbit
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=1
bunny
https://www.bricklink.com/v2/catalog/cat...#T=C&C=152
triceratops
https://www.bricklink.com/v2/catalog/cat...#T=C&C=155
snake short neck:
https://www.bricklink.com/v2/catalog/cat...2#T=C&C=34
snake long neck
https://www.bricklink.com/v2/catalog/cat...9#T=C&C=89
snake 2 heads
https://www.bricklink.com/v2/catalog/cat...02#T=C&C=5
Unicorn:
https://www.bricklink.com/v2/catalog/cat...#T=C&C=157
ox
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=68
bear
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=88
bear 2
https://www.bricklink.com/v2/catalog/cat...4#T=C&C=71
bear 3
https://www.bricklink.com/v2/catalog/cat...#T=C&C=153
Mouse:
https://www.bricklink.com/v2/catalog/cat...#T=C&C=150
Llama:
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=2
Lion mane:
https://www.bricklink.com/v2/catalog/cat...#T=C&C=110
fox
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=4
chick
https://www.bricklink.com/v2/catalog/cat...71pb02#T=C
Giraffe
https://www.bricklink.com/v2/catalog/cat...#T=C&C=103
Horse:
https://www.bricklink.com/v2/catalog/cat...2#T=C&C=42
elephant:
https://www.bricklink.com/v2/catalog/cat...57pb01#T=C
Dragon:
https://www.bricklink.com/v2/catalog/cat...94pb01#T=C
cat
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=11
angler fish
https://www.bricklink.com/v2/catalog/cat...07pb01#T=C
hammer shark
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=86
shark
https://www.bricklink.com/v2/catalog/cat...13pb02#T=C
shark punk haircut
https://www.bricklink.com/v2/catalog/cat...9#T=C&C=39
wolf
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=85
tiger
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=4
snowman
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=1
reindeer
https://www.bricklink.com/v2/catalog/cat...#T=C&C=150
racoon
https://www.bricklink.com/v2/catalog/cat...2#T=C&C=86
wolf 2
https://www.bricklink.com/v2/catalog/cat...5#T=C&C=85
wolf 3
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=11
tiger 2
https://www.bricklink.com/v2/catalog/cat...83pb03#T=C
rhino
https://www.bricklink.com/v2/catalog/cat...1#T=C&C=86
skunk
https://www.bricklink.com/v2/catalog/cat...5#T=C&C=11
octopus
https://www.bricklink.com/v2/catalog/cat...8#T=C&C=48
lobster
https://www.bricklink.com/v2/catalog/cat...=4#T=C&C=4
rabbit
https://www.bricklink.com/v2/catalog/cat...01#T=C&C=1
bunny
https://www.bricklink.com/v2/catalog/cat...#T=C&C=152