I just used segvan to find 3Jjjjj8466bZXCFJQGDk1reaAXwrri39Vz, 3AAaAAMy2auJ1c5wCRj7Qbzx8qshh9cVrx and 3FffFFLntXU14ePkYK3pyASx2Smaw5TfF1

Unfortunately I had to build from master instead of the sipa_grind branch so I think I'm missing out on the huge performance improvements. Is the sipa_grind meant to be working right now?
What do you mean by that?
Native segwit addresses are done by this kind of command:
pc@pc:~/segvan$ ./segvan -r accs
compiled (0): 'accs'
bc1q4ej7d9yaka24ghnfkqhktuxlt8k5tqc2accss5 L86rNnCuGzCxPQZeGJocdzvT6c9spWuijYbjkB4vVwFaA26RckbU
bc1q8accspnwkteu0d4yydxaec0kspcg9es8fqvznp L5wk4v2xUULZrSwjumi1katxLapyqnZ5U1Rh6bqrUeDaeEzBDMQe
bc1q92yk24thhqputldhj4vf3x5npd7rfvaccsadhv L7E2n4P3BGoCSWmm8t9YrMx4UhH1bBALLaZq9xzzR3jeETVvWhzA
bc1qgazsndk2ksqdyl92ph5mmp6vfn8e37d0kmaccs LAGJhxfahkxKbh9SrSNSBj2JnimetaWJVmZ6FusDC7nUrtNaHxWb
And P2SH or standard segwit addresses (P2SH) with following pattern:
pc@pc:~/segvan$ ./segvan -R accs
compiled (0): 'accs'
3NDkUtbB9kQ5zyHP5czbACCsE1eK5mPFfh LKtPttHctrUvKzuST1iREHTSXTPa8JaTnhTYEEQCUpwLwEx2PzyE
3NkaCcsVF9nzamuf7djJxiZ8tnmbiNbiRT LMEeJUeb7PXumEA4bVbTQzGehviu57REmHRJyV62wYjT2GKGrDZk
All of those are done with the same pattern, allthough different kind of options. The later on option with "-R" is supported by more people, rather than the standard segwit addresses shown by the first pattern. Im not that familiar with nullius's segwit address vanity generator, but feel free to quote or PM and ask questions if you have any problems.
Im not really that experienced with this script, and probably nullius will be able to advise you better.
Best Regards, Sellingaccs