Aluminum tape won't work in place of brass shims. The type of metal isn't as important as the thickness. It has to be thick enough to shear the nylon screw without deforming the metal. You can use aluminum from beer or soda cans, that will usually work, but might still be too thin and soft. Soup/coffee cans work well.
If you were building a fiberglass rocket, no question, use shear pins, no shims required.
For a cardboard tube rocket, you have to remember why shear pins are being suggested in the first place. The whole rocket is a system and changing one thing effect most others. I'm suggesting you use friction fit instead of shear pins.
1. The shear pin(s) between the av-bay and the booster are only there to prevent drag separation. On most rockets, a piece of masking tape to add a little friction fit will work just a well as a shear pin. The apogee charge only needs to be enough to open the rocket and get the drogue chute into the air flow. You don't need a big charge that is going to send the upper section slamming into the end of the shock cord. Blow it out or blow it up is the worst method for apogee charges IMHO. Using too large of apogee charge means you need heavier shock cords, heavier eye/U-bolts, more shear pins, and more likely to see damage to your rocket. Using shear pins on the apogee joint also means you need a bigger charge to shear the pins and tends to increase the shock at the end of the cord, which means you need more pins on the nose cone, heavier shock cords, etc. It's all a system.
2. The shear pins at the NC are there to prevent a main chute deploy at apogee when the forward section hits the end of the shock cord after the apogee charge goes off. A small, reasonable apogee charge reduces the need for an extra number of pins. The more pins you use to prevent deployment at the shock hitting the end of the cord, the larger the main charge has to be to shear the pins. The bigger the charge, the more items have to compensate for that. It's all a system.
YMMV, but all of my DD cardboard tube rockets use only friction fit, no shear pins. I never used a shear pin until I built my L3 fiberglass rocket. I know the TRF groupthink is that you have to use shear pins, but you don't. I've had +100 successful DD flight on cardboard tube rockets using friction fit and you can too. Friction fit isn't hard and just as safe as shear pins IMHO. The only fail point is an apogee deployment of your main. You just have to learn how to do the friction fit and not use big apogee charges. Just do a few DD flights at lower altitude, incase you get a main deploy at apogee, until you are confident with your friction fit. Then go for it!