Tom Petersson had a long and very visible history with a variety of Hamer 12-string basses, but the Hamer 12 wasn't really a reality until around the time of the live Budokan albums. Before that time, the multi-string bass sounds were Alembic.
Petersson worked with Jol Danzig at Hamer to build the first 4x3 12-string bass, but the concern of the enormous string tension caused them to build a 10-string bass first (only 2 courses on the lower strings).
The tonal change between the Alembic and Hamer is pretty enormous - the Hamer was recorded with much more distortion. On many of his later basses, there are separate volume controls and output that feed bass and guitar amps and which allow him to blend distortion to clean mix from the bass.
A lot of the basses used in Cheap Trick were in a pool of instruments belonging to the band, nominally owned by Rick Neilsen. I have a bowling pin white 12-string Hamer that was purchased directly from Rick via Gruhn Guitars. It's the bass the Pete Comita used in the Chicagoland concert video around the time Tom Petersson left, was used on tour by Jon Brandt, and in the studio on a number of albums. It's a pretty unusual bass - it has DiMarzio X2N guitar pickups, completely parallel stereo wiring (each pickup is a separate active EQ circuit and volume knob that never join, even on the stereo output jack). It's amazing to play - you'd think that it would be very hard to play an instrument with 3 parallel courses, but this one plays with a beautiful action.
I also had an opportunity to buy the 18-string Modulus that was also built for Tom Petersson. It was built by Modulus at enormous expense, delivered to Petersson who never paid for it. He left it at SIR in LA where it sort of languished in a warehouse for many, many years. At some point they were cleaning out old stuff, found the instrument, couldn't connect with Petersson, and eventually contacted Modulus to find out what it was worth. Since it had never been paid for, it reverted to Geoff Gould at Modulus. I went up to play it and thought about buying it (Geoff knew I was a huge Cheap Trick fan), but it was so odd, unwieldy, and expensive (seems like Geoff, who's a longtime buddy of mine, wanted around $4000) that I just couldn't bring myself to buy it, even with the amazing pedigree. It was better off with Allen Woody - it would have just sat for another 15 years in that gigantic flight case if I had gotten it.
I did end up having a very unique 35 12-string through-body Modulus bass built, which took two trips to NAMM shows and has appeared in Bass Player mag. It's 4x3, built on a Quantum 6 TBX neck form. The body is shaped like a Gibson Ripper bass (I have always loved the shape), with a carved body with a super-thick quilt maple top (so the Ripper body carving is all in figured maple!) and mahogany body. It's 1/2 maple and 1/2 mahogany like the famous Hamer Quadbass that was Tom's main axe for many years. It sounds amazing.
I've always loved multistring basses. I have a Series 8-string from 1980, a Modulus 8-string Quantum, a Hamer 8-string, and even a very old Veillette-Citron 8-string.
David Fung