Combining two suggestions into one post, since there’s a lot of overlap in the discrpition.
Problem: Exploring in rock or sand and widening tunnels for faster travel is aggravating my repetitive strain injury, especially when I go long distances.
Digging Machine, goes in a straight line
Operation: Select, then manually dig once (or use a menu with arrows). The BH rides the machine while it continues digging in that direction until one of the following:
Out of light.
Approaching a change. Rock includes marble, limestone, sandstone, lapis and red marble, since it’s rarely a problem if you dig through them. Stop at least one block before the change, so you don’t risk flooding an area, or confusing maze explorers by opening a new passage, or opening an route for a mob.
About to dig an ore, chest, or anything else. (Might want to use a gem pickaxe or golden shovel or pick.)
It has gone 99 (100? 64?) blocks
Appearance: Small cart with drill in front. Classic cartoon villain machine.
Cost: 2 steel pickaxes for digging, 2 iron for the gears and controls, 1 wood for the platform. It wears out at the speed of one steel pickaxe. Made at level 1 metalwork, or maybe level 1 woodwork.
Tunnel Widener, make tunnels taller (Tall-in-ator? Ceiling raiser?)
Cost: Same as Tunneler
Appearance: Small cart with drill on top. Or maybe drill on the bottom.
Operation: Stand on flat surface. Select, then click on the top left or top right block (or use a menu with arrows). BH rides the machine while it makes the tunnel to the left (or right) higher, until the floor level changes, it runs out of light, or it almost touches a different type of block (as for the tunneler). It keeps going through sections that are already high.