Homebrew: R code to generate a colored table to estimate alcohol by volume (ABV) for printing (A4). See resulting plot at https://imgur.com/gallery/wmd4zzJ

ABVtable.R

library(ggplot2)
library(purrr)

#make a data frame with all combinations of selected ranges of OG and SG
OG = seq(1030L, 1110L, 2L)
FG = seq(1005L, 1030L, 1L)
df <- expand.grid(OG = OG, 
                  FG = FG)
#calculate ABV with all combinations of OG and SG
df$ABV <- 1.05*(df$OG-df$FG)/(df$FG*0.79)*100

#generate plot
ggplot(df,
       aes(x = FG,
           y = OG,
           #ensure labels have the same width
           label = map(ABV,
                       function(x) {
                         if(x >= 10.00)
                           x <- format(round(x, 1), nsmall = 1)
                         else if(x < 10.00)
                           x <- format(round(x, 2), nsmall = 2)
                         return(as.character(x))
                         }),
           fill = ABV)) +
  geom_raster() +
  geom_text() +
  #colors are from RColorBrewer::brewer.pal(3, "Set1")[c(2,1)]
  scale_fill_gradientn(colors = c("#377EB8", "#E41A1C"), guide = "none") +
  scale_x_continuous(breaks = FG, expand = c(0,0), sec.axis = dup_axis(), name = "Final gravity [g/L]") +
  scale_y_continuous(breaks = OG, expand = c(0,0), sec.axis = dup_axis(), name = "Original gravity [g/L]") +
  theme(panel.background = element_blank(),
        axis.ticks = element_blank(),
        axis.title.y.left = element_text(margin = margin(r = 10)),
        axis.title.y.right = element_blank(),
        axis.title.x.bottom = element_text(margin = margin(t = 10)),
        axis.title.x.top = element_blank(),
        axis.text.x.top = element_text(angle = 90, vjust = 0.5, hjust = 0),
        axis.text.x.bottom = element_text(angle = 90, vjust = 0.5, hjust = 0))

#Save in A4 format for printing
ggsave(file = "ABVtable.png",
       width = 297, 
       height = 210,
       units = "mm")