remove factory methods #570

Job	Run time
test (ubuntu-latest, 3.10, jax)	1m 36s
test (ubuntu-latest, 3.10, numpy)	1m 36s
test (ubuntu-latest, 3.10, tensorflow)	1m 46s
test (ubuntu-latest, 3.10, torch)	1m 52s
test (ubuntu-latest, 3.11, jax)	1m 42s
test (ubuntu-latest, 3.11, numpy)	1m 55s
test (ubuntu-latest, 3.11, tensorflow)	1m 43s
test (ubuntu-latest, 3.11, torch)	1m 53s
test (windows-latest, 3.10, jax)	1m 38s
test (windows-latest, 3.10, numpy)	1m 38s
test (windows-latest, 3.10, tensorflow)	1m 39s
test (windows-latest, 3.10, torch)	1m 38s
test (windows-latest, 3.11, jax)	1m 38s
test (windows-latest, 3.11, numpy)	1m 38s
test (windows-latest, 3.11, tensorflow)	1m 38s
test (windows-latest, 3.11, torch)	1m 39s
	27m 9s

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