Rectangular, asymmetrical right handed, round and oval trays with round corners that empty cleanly. 

The rectangular tray size is 80mm by 115mm with the spout width being 32mm. Other trays are a similar size. Walls are 1mm. Scale in your slicer for a bigger or smaller version, mirror for left handed operation. Print at 0.28mm with adaptive layers to get the smoothest corners or use 0.2mm layer height. Scale Z axis only for a taller version for bigger volumes.

A version of each has the spout angled up 10 degrees so that items stay in the tray till you tip it into the container.

The asymmetrical design works well for larger objects that may get jammed up as they enter the spout before emptying. They slide well along the bottom edge.

I used PLA but TPU may be nice if you want to squeeze the spout a bit. Some conductive/ static dissipative or antistatic material may be better to get the lighter plastic parts to flow more easily.

The angled spouts will need support when printing them.

If you want to try just on then I suggest you print the offset version with the angled spout.

If you make the tipped spout version you will notice layer lines across the spout bottom. You can smooth these down so that parts flow more easily and if you paint some clear nail varnish over the sanded section it will be even smoother.

The fusion file can be used for different your own shapes you may want to try, just modify the first sketch (then fix up the following chamfer and fillet errors).

Remix ideas:- 

• A longer spout or another angle.  
• Maybe some finger grips. 
• Add a small motor to vibrate the tray to improve flow. 
• Maybe a flow control flap
• Top edges that curve inwards to prevent bouncy items from getting out