When I make HST's I do not bother with 3/8 and 7/8 but round up to the nearest half inch or whole number. I am going to square up anyway and for me it is more accurate to have a tiny bit more to trim. When I make HST's one at a time I often chain piece and use "The Angler" and sometimes after cutting between the stitched lines my seam allowance is a bit skimpy. If I am going to make 8 at a time I do not want 8 skimpy seams. I find it easier to sew straight on a marked line so I do not bother with the diagonal cutting line and I don't mark the cutting horizontal and vertical cutting lines either as I will be using my ruler to cut.
If I use my Quick Quarter (blue Marking tool I can draw both the stitching lines for each direction without moving the ruler. Sometimes (when I can't find my Quick Quarter marker) I use my ruler and lay the quarter inch line exactly corner to corner to mark. I like to use a Papermate mechanical pencil because the point is always fine and sharp.
When I am cutting and trimming small pieces I use a small cutting mat. When my first large cutting mat wore out I saw that it was getting bald in the same few places and it was when I cut and trimmed small pieces. It is much more economical to replace these small mats.
When I use HST's I almost always press the seams open. I find opposing seams at the corners are just that, opposing, and they push against each other.
This is where I am now. I am trimming the HST's to 2 1/2 inches. that container top left has about 128 that need to be trimmed, next to that is my trimmings and there is my trusty lint roller. I use the lint roller on my cutting mat to pick up the little pieces that transfer to the backs of the pieces I am trimming and then get stitches to them when I sew. In the foreground are stacks of 8 HST's on top of a shoe box cover.
Here is what I have up on my design wall I have 13 more rows to go. When Lori was showing her HST piece she mentioned how she didn't realize show small it would be. Same here! somehow starting with 6 inch squares did not translate to 2 inch finished squares in my mind even though I worked it up in EQ7 and figured out how many I needed.
At least I made enough and I don't have to go back and cut more squares and draw more lines etc. I am thankful that I am not making a large be quilt instead of a 38 inch square baby quilt.
The next one will be larger squares.