Nonmusical scales IX.
Fingering scales by Sápi II.
This section contains Sápi fingering scales that range to two strings.
Let's do the math:
The 1234 fingering combination, as described in the previous section, gives you as many as 24 variations to these four notes.
Also, the number of variations for an exercise that ranges to two strings is 16, which derived from 2^{4} = 16; variation with repetition. (The same formula is mentioned in Scale patterns I. section)
Let's see the variations to four notes.

0000

0001

0010

0011

0100

0101

0110

0112

1000

1001

1010

1011

1100

1101

1110

1111
There are two ways to illustrate the twostring structures. The first one...
...And the second with digits
1000
Given these conditions, you will have 24 x 16 = 384 fingering scales, out of which the two scale groups that only have a range of one string are excluded (0000 and 1111, which is 2 x 24 = 48). This will give a result of 384  48 = 336 scales, which will all be modeled below.
Zoli SĂˇpi also found a very significant correlation in the picking algorithms. Although constant alternate picking is what you always stick to, one can differentiate between alternate picking algorithms in relation to the given fingering combination, namely either starting the alternating picking sequence with

a downstroke

or an upstroke.
The different alternate pickings are indicated with different colors.
We have altogether 14 twostring scale groups (16 2 = 14); the standard 24 fingering combinations could apply to all of them.
Zoli Sápi grouped the scales by the number of notes on each string. For example 13 means 1 note on one string, and 3 notes on the other one.
13 scales
1000
0100
0010
0001
Here is a video for the 4231 fingering combination:
31 scales
0111
1011
1101
1110
22 scales
1100
Here is a video for the 4231 fingering combination:
1010
Here is a video for the 1234 fingering combination:
1001
0110
0101
0011
What's the next exercise? The 3string fingering scales!