Yay! I just had success with impriting a more-or-less complex pattern into the magnet.

Making the coil wasn't fun though.

I 3d-printed a plate with a channel for the coil. Then I wound a coil of right length between two screws, and packed it into the channel. It went like 1) pack a small piece; 2) put some superglue, and push on top with polyethylene bag... repeat till done. Very annoying!

But the results were worth it!

The coil measures 2.43 Ohm, 73 uH, and has 20 loops (turns). It took a pulse of about 500 A to get appreciable magnetization. The capacitor bank was charged to 2 kV. It was ridiculously dangerous. And unfortunately, I want more!!