Hi John
I would take two small pieces of steel or aluminum and place together in the drill vice, then drill a hole in the join line creating two 180 degree halves. Using a drill just slightly oversize compared to the laser body.
then wrap the laser body with masking tape to fill the gap and clamp the two pieces over the lot.
Its a delicate balance between too tight and too loose but a wrap or two of tape and your part will be a tight fit in the custom made clamp.
You may have to make two clamps. if both ends are hard to hold.
I have used this method many times On bigger stuff I dont worry about protective tape.
I used it to unfreeze a rusted in shaft a while back 30mm in diameter. there I used a metre long bar of 50 x 25mm sq with a small length for the other half of the clamp after cross drilling a couple of M12 set screws and nuts were used to clamp the pieces together. I bored a 30mm hole through the two pieces while they were clamped together. (Using a piece of cardboard to create a gap)
The shaft was not damaged. The long leverage allowed me to work the shaft back and forth (with lots of oil) to clear the rust. and remove the shaft.
Cheers
John