Useful things to 3D print

Create a cylindrical control knob 32 mm in diameter and 18 mm tall, with twelve 2 mm deep grip flutes evenly spaced around the circumference, a 6.2 mm D-shaped shaft socket 12 mm deep with a 5.4 mm flat, and a 1 mm chamfer on the top edge.

The D-shaft socket is 0.2 mm over nominal so it presses on rather than binding. Measure the flat on your own shaft.

Create a replacement appliance foot with a 30 mm diameter base, 16 mm total height, a 20 mm diameter upper post, an M6 threaded blind hole 12 mm deep from the top, and a 2 mm fillet where the post meets the base.

The base fillet is what stops it snapping off under the weight it is carrying.

Create a retaining clip 24 mm long, 10 mm wide and 3 mm thick, with two cantilever arms 12 mm long and 1.6 mm thick ending in 1.5 mm barbs, and a 4.5 mm mounting hole in the flat base.

Thin arms flex, thick arms snap. 1.6 mm is four perimeters at 0.4 mm and about right for PETG.

Create a drawer divider 280 mm long and 60 mm tall with 2.4 mm walls, a T-shaped cross section with a 40 mm wide foot, and three 20 mm wide slots cut 30 mm deep from the top edge at 70 mm intervals.

Measure your drawer interior and subtract 1 mm so it drops in without forcing.

Create a wall-mounted tool holder, 150 mm wide, 40 mm deep and 25 mm tall, with five 12 mm diameter holes spaced 28 mm apart along its length, a 4 mm thick back plate, and two 5 mm countersunk mounting holes 120 mm apart.

Countersunk holes let the screw heads sit flush against the wall.

Create a stepped pipe adapter 50 mm long, with a 25 mm outer diameter barbed spigot 20 mm long at one end, a 32 mm outer diameter socket 20 mm long with a 28.4 mm bore at the other, and a 3 mm wall thickness throughout.

Adapters between two sizes you happen to own are the classic case where no model exists to download.

Create a rectangular enclosure base 95 by 65 mm external and 30 mm tall, with 2.4 mm walls and floor, four internal corner bosses 6 mm in diameter with 2.5 mm pilot holes positioned 5 mm in from each corner, a 12 by 7 mm cutout centred on one long side, and a 0.5 mm chamfer around the bottom edge.

The cutout is a USB-C panel opening. Move it to where your board actually puts the socket.

Create a hexagonal standoff 12 mm long across 6 mm flats, with a 2.5 mm pilot hole through the full length and 0.5 mm chamfers on both ends.

Chamfered ends stop the first thread burring over when the screw goes in.

Create a DIN rail mounting clip for 35 mm top hat rail, 40 mm wide and 6 mm thick, with a fixed upper hook, a 1.8 mm thick sprung lower arm, and two 4.5 mm mounting holes 25 mm apart on the flat face.

The sprung arm needs to flex, so keep it thin and print it lying flat so the layers run along the bend.

Create a standard metric involute spur gear with 30 teeth, module 1.5 mm, 20 degree pressure angle, a 6.2 mm centre bore and 8 mm face width, with small root fillets.

Module and tooth count set the size. Do not also specify a diameter or the two will conflict.

Create a drilling jig 100 mm long, 30 mm wide and 12 mm thick, with a 20 mm tall locating lip along one long edge, and five 6 mm diameter guide holes on the centreline spaced 20 mm apart.

The lip registers against the workpiece edge so every hole lands in the same place.

Create a rigid shaft coupler 28 mm long and 22 mm outer diameter, with a 5.2 mm bore at one end and an 8.2 mm bore at the other, and two M3 grub screw holes per side positioned 90 degrees apart.

Both bores are 0.2 mm over nominal, which is the FDM allowance rather than the shaft size.

Create a monitor riser leg 120 mm long, 90 mm tall and 60 mm deep, with 3 mm walls, an open underside, a 20 mm wide cable channel through the back face, and 4 mm fillets on all outer vertical edges.

Open underneath means no wasted infill and no support material.

Create a circular drainage tray 160 mm in outer diameter and 22 mm tall, with a 3 mm wall, a 3 mm floor, a 10 mm wide flat rim, and three 4 mm tall support ribs across the floor.

The ribs hold the pot clear of standing water. Print in PETG, which handles moisture better than PLA.