This topic of case declension is taught many ways in text books. While looking over this in Soumen Mestari, I realized that while they have some great examples, my engineering mind wanted more... so this is what we have:

LOCATION MODEL — bussipysäkki

FORM = STEM + ADDITION

CASE = LOCATION_TYPE + MOVEMENT_DIRECTION

Core Table

Label	Direction	Case	Stem	Addition	Form	Meaning
S	TO	Illative	bussipysäkki	-in	bussipysäkkiin	into the bus stop
S	AT	Inessive	bussipysäkki	-ssä	bussipysäkissä	in the bus stop
S	FROM	Elative	bussipysäkki	-stä	bussipysäkistä	out of the bus stop
L	TO	Allative	bussipysäkki	-lle	bussipysäkille	to the bus stop
L	AT	Adessive	bussipysäkki	-llä	bussipysäkillä	at the bus stop
L	FROM	Ablative	bussipysäkki	-ltä	bussipysäkiltä	from the bus stop

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SEMANTIC MODEL

                    MOVEMENT AXIS

                 TO           AT           FROM

INSIDE (S)    Illative    Inessive     Elative
OUTSIDE (L)   Allative    Adessive     Ablative

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MORPHOLOGY MODEL

S-series

TO      -> -in
AT      -> -ssa / -ssä
FROM    -> -sta / -stä

L-series

TO      -> -lle
AT      -> -lla / -llä
FROM    -> -lta / -ltä

Hopefully this helps folks who think about this in a more engineering way.