Which tin cans do you mean?

The West (not just NATO and not just EU) are being very generous with NLAWs, Javelins, and Panzerfaust 3 among others that can take out the best Russian tanks. Ukraine also makes a very effective stugna-p that's tripod mounted and allows control from a safer location. Not only are these weapons much cheaper than any Russian made tank, they don't take much training on the order of a few hours to a few days depending on the weapon, and they are being produced in many western countries and donated to Ukraine who provides the man power to use them.

So take a motivated Ukraine citizen, train them for a weekend, and they can periodically take out a Russian tank at around $1M with 3 expensive people inside. I've seen studies showing that out of 110 shots (in the Ukraine war) that achieving 90 kills wasn't unusual. In particular the better weapons are fire and forget, removing the skill needed to accurately hit the tank. I have noticed that Ukraine military are getting really good with the stugna-p and will steer the weapon in a different direction then steer the weapon on target at the last second. Presumably to hit the most vulnerable part of the tank and hide their launch location.

If you mean cheaper armored vehicles that opens up quite a few additional weapons like RPGs, recoilless rifles, Bayraktar tb2 drones, etc. For the less armored or unarmored anti-material rifle rounds can be quite effective. In particular Ukraine has had great success just shooting out tires of armored vehicles and trucks. Even replacing a truck tire at the end of a long supply line is a substantial logistical burden that Russia is not handling well.

Basically it's not going to work having Russia produce more tanks than the Ukraine can destroy. Without a well trained and motivated army that can implement a combined arms attack the armor is just sitting ducks for modern weapons. This is a huge setback for Russia whose military doctrine depends heavily on tanks. It bodes poorly that they are calling in the reserves, which are basically untrained (unlike the reserves in other countries), even compared to the poorly trained soldiers already in the field. Running out of solders just 4 weeks in is pretty bad, and losses have already exceeded much longer Russian invasions.

Russia does produce it's own tanks, however they need to import parts, which has been a big bottleneck and last I heard tank production had stopped in the only tank factory in Russia.

As far as planes go, yes Russia makes planes and helis, but they are significantly more complicated than tanks and depend on more imports than the tanks do. They are also risky to fly when the Ukraine is so well supplies with stingers, starstreaks, and anti-air systems like the s-300. Ukraine has also had growing success taking out Helis with anti-tank weapons.

The longer the war goes, the worse it's going to get for Russia. Sanctions, decreased GDP, trying to compete with the sum of the economies in the EU and NATO. The brutality demonstrated is providing significant incentive for any nearby country that doesn't want to see a Ukraine like invasion in their future. Looks like Finland and Sweden that were generally neutral and promised not to supply weapons to Russia's adversaries and not join NATO have changes their minds because of the Ukraine invasion. Keep in mind that the GDP of the EU is around 18T and USA is 21T. Russia was around $1.5T, before the invasion and sanctions. Even ignoring loss of life, estimates put the daily cost to Russia for the war is around €20 billion per day. Clearly even a 100 day war, even without sanctions, is going to be VERY expensive for Russia. Even just Finland and Sweden have around 50% of the GDP of Russia and needing a 3:1 ratio for invaders vs defenders is a common rule of thumb.