On a kind of related note, there were catapult launchers used during the 1944 Warsaw Uprising to lob grenades and Molotov cocktails but the Resistance also apparently made crossbow- and pipe-type launchers for Molotovs as well.
There's a reference to such devices on the following webpage: -
http://www.polishresistance-ak.org/25%20Article.htm
There's nothing but the barest details but they can be found under the section titled
WEAPONS PRODUCED BY THE HOME ARMY which is just past the half way mark on the page then proceed to the sub-section titled
Flamethrowers and catapults for Molotov Cocktails and hand grenades:
There's an example of a catapult-type launcher in the Polish Army Museum in Warsaw that is basically a set of leaf springs and a hand-crank, fitted with a cradle for the bottle or grenade.
https://commons.wikimedia.org/wiki/F...g_Catapult.JPG