My own design

To make this Flying Flea of me accessible to wheelchair-users, i hoped to keep the center of the cockpit free of obstacles. This way the disabled pilot can slide his feet forwards easily.

Making a good sidestick seemed not to be that easy. Many steering systems count on the flexibility of the cables to correct the fact that the cables don't run in the axis they should be if you don't want that pitch influences the steering of the rudder or vice versa. The old HM14 is such a system that counts on cable elasticity.

I wanted to have my system free of interference between both steerings (pitch and yaw) and ...i wanted it to be simple to make.

This is the result.

 

The yellow parts are guides in which the tubes can slide and turn for the metal color part or just turn for the green part in the rear.

The green parts are levers which are connected to the control-areas. Front wing and rudder. The left lever is connected with the front wing.

The blue part is just a connection-tube. It has a normal hinge at the green part. It has a ball hinge at the stick part.

The red parts are a wide hinge to allow the stick to move forwards and backwards without the green part at the right to follow that movement. The two yellow tube guides hold that green part on its place. The green part can only rotate.
The hinge is made extra wide to minimize possible play in the hinges

The system will be placed at the side of the fuselage. The stick will be angled in neutral position. If the stick movement limit is at 20°, than the stick will be at 30° from the fuselage side in neutral position. Just to be sure you have place for your hand.

My only fear was that it might have been hard to do the needed force on the stick with just one hand. But i got many comments of Flying Flea pilots that those forces are not really that hard. To make sure we placed the rear landing wheel in the axis of the rudder to make sure that the rudder touching the ground or a obstacle will not result in a change of steering.