Right, your joints aren't what they once were and getting up and down to sow those larger seeds like beans is beginning to give your back a bit of bother. Get's harder each year for some. Well, I had this 'ere idea this morning.
All you need is a 3ft long piece of 2" dia plastic pipe and a marker pen. What you do is mark the pipe up from the bottom to the depth you require. Then you push it in the ground and lift out a plug of earth. Tap the pipe with your foot and drop the soil alongside the hole. Position the pipe over the hole and drop a seed down it into the hole. Use the pipe to push the mound of soil back into the hole. Boom Boom.
(Got the brain working on a semi automatic full row plastic pipe assisted seed planter now.)
HMMMMMMMMMmmmmmmmmmmmmmmmmmmmmm??????
I get days like that where you spend hours on building something that doesn`t work while your weeds are growing or you see a better well made version in the shop that YOU had JUST invented! and never seen it before! mad a cannon once then thought of a multi one like your pipe and lit and kaboom the whole lot blew up at once! hope your pipe works!!!