Development and production of original tanks requires engineering and industry resources that were uncommon at the time. For a small country, the path to owning tanks would be to buy them from a country that exported them and then, if you had the money and the talent, modify them to suit your needs better. Your options were:

Sweden: Sweden inherited a lot of German engineers after WWI, so tank development thrived in the immediate post-war years. Its most notorious export tank was the Landsverk L-60. Austria bought one for trials, Ireland bought two, and Hungary bought one and then a license to produce them under the name Toldi.

Czechoslovakia: Built some of the best pre-war light tanks in the mid to late 1930s, until annexation by Germany. Sold LT vz. 38 tanks to Switzerland, Romania, Bulgaria, and the USSR. Interestingly enough, Sweden also bought Czech tanks, as they were cheaper than domestic designs.

Britain: The "6-ton" Vickers Mk.E was one of the most popular export tanks of the interbellum era, most famously bought by China, Poland, and the USSR, as well as a score of other countries. Carden-Loyd tankettes were another popular export item and were also used as the foundation for Polish, Soviet, and German tankettes.

France: Various "colonial remixes" of the Renault FT were available, including the Renault NC which went to become the basis of Japan's tank industry. Later, France would sell the Renault R35 to Poland and Romania.

USSR: A batch of T-26 tanks was sold to Turkey, plus tanks and armoured cars were sent to Spain to fight in the civil war.

USA: Christie was willing to deal with anyone, selling tanks to the USSR, Poland, and the British.

One notable exception is the Nahuel tank developed in Argentina. Even though it's quite clearly inspired by the Sherman, the design appears to be original.