Now obviously the factor of the insane costs associated with capital ships was a major factor in driving Britain, the US, and the rest to the table is not quite on the same scale for a tank or an aircraft. And air power and armored warfare were still in their developmental stages but were there any movements or ideas to extend limitations to them as well.
Mostly interested in conventional weapons here as opposed to the discussions and process leading to the inter war Geneva Protocol relating to gas and chemical warfare, etc.
Yes, there was.
A series of discussions in Geneva in the late 1920s were undertaken to do to land forces what the Naval treaties did to ships. I have only tangentially encountered it in my research on French tanks. The development process for the Char B1 was lengthened considerably because the discussions included a proposal to limit the weight of tanks. As a result, the French government created the Char D2. If the treaty was passed, D2s would be built instead of B1s. If not, (and it happened that the talks failed), B1s would be built. The result was a rather ponderous and somewhat obsolescent design which had been kept on the shelf for a few years, instead of simply starting anew when the negotiations collapsed.
I hadn't encountered it before, as no other country at the time was seriously trying to build tanks in that weight class.
There were efforts to limit, or even entirely abolish, air forces, particularly around the Geneva World Disarmament Conference of 1932-34. In the inter-war period writers like H. G. Wells and military theorists such as Douhet and Groves presented nightmare scenarios of unstoppable bombers wreaking catastrophic devastation on both military targets and civilian populations using high explosives, incendiaries and poison gas. To defend against such a possibility a country would need to possess a powerful bomber force of its own as a deterrent, the essence of Stanley Baldwin's famous "the bomber will always get through" speech of 1932: "The only defence is in offence, which means that you have to kill more women and children more quickly than the enemy if you want to save yourselves."
Limiting military aviation was problematic; there were proposals to restrict overall numbers or weight of aircraft, similar to the naval treaties, but with aircraft being much easier to conceal than ships these would have been difficult to enforce. A proposal to limit the weight of bombers to three tons was taken seriously enough by the RAF to set that maximum weight in a 1932 requirement for new bombers, B.9/32, delaying the development of the (ultimately much heavier) Vickers Wellington and Handley Page Hampden; Baldwin also mentioned slightly more fanciful possible issues in his speech: "The amount of time that has been wasted at Geneva in discussing questions such as the reduction of the size of aeroplanes (...) have really reduced me to despair. What would be the only result of reducing the size of aeroplanes? As soon as we work at this form of warfare, immediately every scientific man in the country will turn to making a high explosive bomb about the size of a walnut and as powerful as a bomb of big dimensions, and our last state may be just as bad as the first." Restrictions would also have to apply to civil aircraft, as the concern was that airliners could rapidly be converted into bombers (not entirely unfounded, considering e.g. the dual role of aircraft like the Ju 52).
Other proposals were to place all aviation under international control; Baldwin spoke of the possibility of international control of civil aviation to allow for disarmament, Philip Noel Baker produced a detailed plan for an International Air Police Force in 1934, the Labour manifesto of 1935 included a promise to "propose to other nations the complete abolition of all national air forces, the effective international control of civil aviation and the creation of an international air police force". With the League of Nations ineffective and disarmament efforts failing, though, these came to naught.
Brett Holman's [The Next War In The Air] (https://airminded.org/publications/the-next-war-in-the-air/) has a good section on internationalism and disarmament, and his [Airminded blog] (https://airminded.org/) has several excellent pieces like [For What?] (https://airminded.org/2015/03/21/for-what/), with a rather [striking poster] ( http://airminded.org/wp-content/uploads/2015/03/abolish-all-war-aeroplanes.jpg ), and [World police for world peace] (https://airminded.org/downloads/download-info/world-police-for-world-peace-british-internationalism-and-the-threat-of-a-knock-out-blow-from-the-air-1919-1945-pdf/).
